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Human Body​


What is the human body up of?

Human Body- 60 70% of our body is made up of water The remaining part of the body is made of chemicals, bones, veins and arteries All these are made of cells, which are the basic building blocks the body. The cells have a cell membranecaround them which lets exchange of food and water. Most of the activities of the img ber maar on the Human Skeleton cells are controlled by nucleus of the cell

Is the composition of every human body the same?

The average human body is made up i. aprrox 60% of water but that could van in an infant to about 75%. The percentage of water content in the bi also depends on the cholesterol level the cholesterol is high then, the
percentage of water can be as low as 45%. Skull

Human Body


Why is the brain called the most important part of the body?

The brain is called the most important part of the body because it controls all the functions of the body. It receives messages from the organs and then instructs Brain them to take necessary action.

What is the function of the brain?

The human brain is perhaps the most complex of organs, boasting between 50-100 billion nerve cells or neurons that constantly interact with each other. These neurons carry messages through electrochemical processes, meaning, chemicals in our body move in and out of these cells and establish an electrical current. Nerve Cell

Human Body


1.What is the structure of the eyes?

The eyes are two tough balls containing a jelly like substance of Humon Eye called vitreous humour. At the front of each eye is a eye is called iris. The round dark part in the middle distransparent covering called cornea. The coloured part the called pupil. The pupil is also known as the window of the The basi the ear pin the eye and the lens lies just behind the pupil.

2.How do we see?

The curved surface of the eye and the lens bend the rays focus them into a clear image ontos retina. Cells in the Corneo Lens adjust shape according to distance Tetina send messages and the optic en to the brain The brain the
Refina combines all de Light Rays views and gives an impression of the pic
The picture formed on the retina is inverted but the brain interprets the right image up. Inverted and Small Image

Human Body


1.What is the structure of the human ear?
Cochie The ear consists of three basic parts – the outer ear, the middle ear, and the inner ear. The outer ear is called pinna. It collects and transmits the sound to the middle ear through the auditory canal. At it’s end there is a thin membrane called the eardrum or tympanic membrane. The
eardrum moves inward and outward as the compression or rarefaction reaches it. In this way the eardrum vibrates. These vibrations are amplified by the three bones namely the Estacion Tube Forum hammer, anvil and stirrup in the middle ear that transmits these vibrations to the inner ear. Inside the inner ear, the vibrations are converted into electrical signals by the
cochlea. These electrical signals are sent to the brain via the
auditory nerve and the brain interprets them as sound.
2.How does Sound reach the ears?
Sound is made up of pressure waves which can travel through air, water and solid objects. Our ear reacts to the vibrations caused by the movements
of air. When these sound waves strike the outer ear (called pinnae) they are
funnelled down the ear canal to the eardrum which then starts to vibrate.

Human Body


1.What are teeth made of and what are the different types of teeth?

Crown of LIT Wh ar Jawbone Periodontal fibre Cementum The inner core of the tooth is the pulp which is a soft tissue Th or b Ti si with blood vessels and nerves. Surrounding the pulpis The outermost layer is called the enamel, which is the middle layer called dentine which is soft yet hard as bone hardest substance.

2.What is the tongue made of and what is its function?

Lingual Tonsil Palotine Tonsil its function
The human tongue is a large muscle and is full of blood vessels. The tongue aids in moving food in the mouth, Circumvallate chewing and swallowing. It Papillac gives us the ability to talk li the principal organ of taste 1 Foliate Papilloe Filiform Papillae Fungiform Papillae tongue rolls food into balls an
pushes them to the back of the buccal cavity for swallowing Tongue

Human Body


1.what is liver and what are its main functions?

The liver is one of the largest single organ in the body. It is reddish brown in colour and is situated to the right of the stomach. It has many functions. It produces substances that break down fats and convert glucose to and makes certain amino acids (the building blocks of glycogen. It also produces urea (the main substance of urine) proteins). The liver also filters harmful substances from the blood (such as alcohol). It also acts as storage of vitamins and minerals (vitamins A, D, Kand B12) and maintains a proper level of glucose in the blood. The liver is also responsible for producing cholesterol. It produces about 80% of the cholesterol in the body.

2.What is kidney and what is its main function?

The kidneys are a pair of small bean shaped organs found in the back, just under the ribs. The main function of the kidney is to
purify the blood and also control the body’s water content. The kidneys recycle all the reusable substances from the blood. It gets rid of the waste in the form of urine.

Human Body


1.What is the function of the heart?

The heart is of the size of our fist and is situated slightly towards the left in the chest. The main function of the heart is to pump blood throughout the body. This is done by contracting and relaxing the muscles of the heart.

2.What are the different parts of the heart?

The heart is divided into four main chambers namely left right auricles and the left and right ventricles. The left auricle receives oxygenated blood from the lungs. This blon then passes to the left ventricle from where it is sent to ao the biggest artery. From here the blood is circulated throughout the body. The right auricle receives deoxygenated blood along with the waste products and it is passed to the right ventricle and then into the lungs where it is purified.

Human Body


1.What are lungs?

Lungs are a pair of soft, spongy bags and the right side. Each lung contains
inside the chest, one on each on the left millions of air sacks, which gets filled
and enlarged when air is inhaled.

2.what is respiration lungs?

All living organisms breathe in order to take oxygen from the atmosphere and breathe out to exhale carbon dioxide from Bronchi the body. This process is called respiration

3.What happens when we breathe?

When we breathe, the oxygen inhaled travels through the windpipe or trachea into two large tubes called the bronchi. These tubes lead to the lungs from where the air travels into a system of small air passages called bronchioles. Finally, the air reaches millions of tiny air sacs called alveoli inside the lungs. Inside the alveoli are small blood vessels which take the oxygen into the blood. While the exhaling, carbon dioxide is taken from the blood and passed Lung Function out from the air sacs through the mouth.

Human Body


1.What is the spinal cord?

The spinal cord is a bundle of nerves whic down the middle of the backbone. It is on the body in pairs from either side. here that the nerves branch off to all penso SKIN Why do Skin ist protectie from the to keep infectio rays an make the bod which tempe wha

2.What is the purpose of the Spinal cord?

The spinal cord is located inside the vertebral column. It is a link between all the nerve signals travelling between the brain and the body. The spinal cord can work independently, sending out responses to the muscles directly. If the spinal cord is damaged it can lead to paralyses and even death in extreme cases.

3.What is the Spinal cord made up of Swot Gland Normal Spine Sideways Deviation?

The outer side of the spinal cord is a collection of axons of nerve cells and is called the white matter. The inner portion is made up of the main nerve cell, which Hair Room is called the grey matter.

Human Body


1.Why do we have skin?

Skin is the outer waterproof, from the outside world. It also helps protective coating covering our body to keep out harmful germs and rays and also uses the sunlight to infections. It protects us from harmful make Vitamin D which is useful for the body. The skin contains nerves which respond temperature and pressure. to touch pain,

2.What is the skin made up of ?

Hole Epidermis follide Sweat Gland Swed e The skin is made up of two layers namely the outer epidermis and the inner dermis, The epidermis is the thin outer layer made of tough protein called keratin. Below the epidermis is the dermis which contains blood vessels and nerve cells. Beneath the dermis is the layer of fat which helps to keep the body warm. Skin also contains sweat glands and hair roots which help to control the body temperature, Har Darms Blood vessel Cross Section of Skin

Human Body


1.What are nails made of and What is their function?

BLO What Our nails are made out of keratin. Keratin is made out of dead cells packed real tight together that is why it is hard. of Blood of ce made of a tough protein called cartilage are Inside o Fingerin cells produced from alsc Anatomically fingernails and toenails, which are living skin cells in the fingers and toes. The fingernail as The fingertip has many nerve endings in it allowing as a protective plate and enhances sensation of the finget nail acts as a counter force to the fingertip providing even receive volumes of information about objects we touch. The us to more sensory input when an object is touched.

2.Why does hair turn gray?

Hair turns gray as we age because the follicles at the base, the hair shaft cease to produce melanin. Each follicle contains a finite number of pigment cells. These pigment cells produce melanin, a chemical that gives the hair shaft the visible strands, its colour. The darkness or lightness of the hair depends on how much melanin each strand contains. With age, the pigment cells in the follicle gradual die off. As they do so, that strand will no longer contain as much colour and will show up as silver, gray, or white as it grows. Eventually, all the pigment cells will die and the hai becomes completely gray.

Human Body


1.what is blood made up of?

Colle Red Blood Colts of cells called the RBC (red blood Blood consists of mainly two types Polls cells) and WBC (white blood cells). Besides these, the blood also contains platelets. Platelets are tiny particles which form a clot when there is a cut The RBC, WBC and blood platelets float in a liquid called the plasma. Plasma contains the food required by the body. RBC contains red protein called haemoglobin WBC helps in fighting Blood Clot seen by an electron microscope infections and diseases.

2.What is the function of the blood?

Blood carries food and oxygen to cells, it carries waste away from cells, and serves as a carrier for various disease- fighting cells such as the white blood cells. It also has a means of puncture-proofing the body; it clots, sealing up small holes quickly. Blood is also important in maintaining a constant temperature in our body.

Human Body


1.What are the different types of muscles?

Muscles are fibres which help in the movement of the body. There are three types of muscles found in the human body, smooth VEI Wha Vein bloc bloc the pul fro ha su are muscles, cardiac muscles and striped muscles. Smooth muscles are found in the heart region. Striped muscles a the wall of intestine. Cardiac muscles are muscles which control movement. Mustos also divided into voluntary and involuntary types. Voluntary muscles are those over which di A a individual has control. Involuntary muscles are those over which an individual does not have control. Smooth Muscles Striped Muscles Cardige

2.What are muscles made of and how do they work?

Muscles are all made of the same material, a type of elasti,
tissue, like the material in a rubber band. Thousands, or
even tens of thousands, of small fibres make up each musi
The main function of the muscles is to make the body mor
and connect bones together.

Human Body


1.what are veins?

blood. Most veins carry deoxygenated Veins are pipes in the body used for carrying the blood) to the heart. Only the four blood (cells having taken the oxygen from from the lungs. Most of the large veins pulmonary veins carry oxygenated blood have flaps which act as valves to make sure that blood flows in one direction VEINS ARTERIES away from the heart. Arteries transport

2.what is an artery?

An artery is a blood vessel which carries blood oxygenated blood around the body. Arteries branch into an arteriole which further branch into microscopic capillaries. Arteries have thicker, muscular walls than the veins and the pressure of blood is also higher. One of the reasons for high blood pressure is over-thickening of the artery walls.

3.What is a capillary?

The smallest type of blood vessel is called a capillary. It connects the smallest arteries with the smallest veins. Capillaries carry oxygen-rich-blood to the tissues. It also carries waste products such as carbon dioxide to the lungs and kidneys for elimination from the body.

Human Body


1.What is digestion?

Mouth Digestion is the process by which lood is down into substances which can be abseite by the body. When food is swallowed. It is ground into smaller pieces by the teeth the help of saliva. After this, food is passen through a tube called the oesophagus tot stomach. Here, food is further processed by hydrochloric acid. The half digested food Small Intestine Large Intestine processed known as chyme goes into the small intestine, where it is further with the help of bile and other juices, Finally, the digested material goes into the ileum, where it is absorbed into blood

2.What is excretion?

Excretion is the process of getting rid of food, which cannot be digested. The undigested food is passed into the large intestine. The colon, which is the main part of the large intestine, converts the semi-liquid chyme of undigested food i
solid waste, by absorbing water. This is passed into the rectum, where it remains some time, after which it is finally ejected on of the body as faeces.

Human Body


We can chew our food and breathe at the same time. This is ossible ecause the nose is separated rom the muth by a bone called he palate. The nose is a biological ir conditioning unit. It contains hair hich traps large dust particles. If here is a lot of dust in the air, we ay sneeze to remove it from the ostrils. If cold air enters the nose, it is armed by the blood in the several apillaries, which are found close to the alls of the nasal cavity. These blood vessels also rovide water which humidifies the air if it is too dry. e can feel the difference between cold and dry air which is breathed nto the lungs via the nose and the ame type of air breathed in via the outh. The air, then, passes into the hroat and down the windpipe trachea). The entrance to the trachea s protected by a valve, the epiglotis, hich closes when we wallow food or drink. n this way, the air assage is only locked for a econd. So e do not ave to hold ur breath.


Muscles usually work in pairs. A muscle can direction. So, it eeds another muscle to pull in the opposite direction in order o return a bone to its original position. The best example of a pair of muscles working together can be seen in the human arm. The muscle at the front of the arm is called the biceps muscle. The muscle at the back of the arm is called the triceps muscle. When the biceps muscle is working (contracted), the triceps muscle is relaxed. When the triceps muscle is contracted, the biceps muscle is relaxed. This is called the antagonistic action of muscles because they are always working in opposite ways. The contraction of the biceps muscle bends the om The contraction of the triceps muscle straightens the arm. There are muscles in the legs which work in the same way to bend the knees, ankles and toes.


Nerve impulses are tiny electrical signals body and convey nformation. Each which travel through the nerve cells of the nerve cell has small projections called dendrites. These dendrites extend from the cell body and responsible for receiving messages from the other nerve cells. The impulses, then, travel down along the axon to the terminal branches. There, the impulses are carried Out are across the gap to the next neuron by way of chemicals called neurotransmitters . These chemicals are capable of binding to the receptors found in the dendrites of the next receiving nerve cell. Once, a number of receptors on the receiving cell have chemicals bound to them, they trigger changes in the receiving neuron. This enables it to
send the electrical signal down its axon. When the signal reaches the end of the axon, it again triggers the release of neurotransmitters that repeated over and over in are, then, picked up by the next receiving nerve cell. This process is rapid succession More 62 T.


A hiccup is a sharp, usually repeated sound made in the throat. It is by a sudden movement of the diaphragm. This happens when you eat too much, drink bubbly drinks like soda or swallow too much air. When you eat very hot food, it may imitate a passage in your digestive system. It may even be the reason for the forma-tion of gas in the sto-mach. This gas presses against the diaphragm. The diaphragm is an organ which separates the chest from the stomach. It tightens up and pulls air into the lungs. Because it has tightened up, the air cannot get through all the way to the lungs. It is stopped short by the diaphragm. You feel a dump when this happens. This dumping feeling is described as hiccups. So, hiccups are a way of telling you that your body is trying to get rid of the hot food or gas in the stomach.


that he/she can do certain things better When a person is left-handed, it means with the left side of his/her body than with the righi side. But the question arises as to how a person is left-handed. One theory rests on the centres of the two halves of the brain, i.e. the left half and the right half. It is believed that the left half of the brain predominates over the right half. This theory is based on the fact that the nerves from the brain cross over at neck-level to the opposite sides of the body. As a result, the opposite sides of the body are supplied by the opposite sides of the brain. The left half of the brain controls the right half of the body and renders it more skillful while reading, writing speaking, and working. It
makes most people right-handed. On the other hand, it is just the reverse in case of a lett handed person. The right half of the brain controls the left half of the brain and, hence, a person works est with the left side of his/her body.


the es due to the sweetecting bacteria. Your teet smell too bad because the bacteria become thodied to the sweat on your feet and ston feeding on it. The excretion of the bacteria hos o Strong odour that couses your teet to smell bod. What makes the Suation even worse are the shoes and socks which trop the sweat on your skin. Now, the bocteria have their favourite kind of environment which is donk ondomp inside the shoes. You sweat all over your hores rich have comparable number of sweat glonds but they do not inic W52 The ser is your socks and shoes. The sweat your feet Ducrete con teosily escape into the air like the sweat your hands excrete all collecs on your skin and in your socks. The bacteria love this dark, domp feast and have a sort of feeding frenzy. When you toke off your shoes, the smell that hits you is all the excretion made the bacteria. It is collecied on your feet and in your socks and shoes. Some people’s feet smell more than others because of the simple reason that these people sweat more than others.


A headache is simply the painful symptom of an with multiple auses. There may be various Couses for a headache, underlying dison i only indicates that there is a disorder somewhere in the
body or in the nervous system Common causes of a headache are tension, migraine, eye strain, dehydration, low blood- sugar and sinusitis. A headache does not mean that there is pain in the actual brain matter contained in the skull. It is actually the pain felt by the sensitive coverings of the brain, and of the large veins and arteries which drain fluid from the brain. Sinus, tooth, eur and muscle pain also produce headaches by radiating the pain to these sensitive coverings when they get tensed. Similarly, when the muscles spanning the neck and the base of the skull contract, headaches may occur. Another reason for headaches is when people experience the effects of sudden physical and emotional trauma.


Except for showing that you are angry, your eyebrows do a lot to protect you. You do not know that. Well, it is true. The tiny, ne ne of hoir above each of your eyes is called the eyebrow. It plays overy important role in keeping moisture out of your eyes
When it rains or when sweat drips down from the forehead, the eyebrows divert the flow of water or sweat away fror your eyes to the side of you face. This keeps your eyes dry The orch shape of the eyebrows enables you to see dearly while it is raining. Besides, it also keeps away perspiration from dripping into your eyes and causing irritation or burning sensation. Like your Eyelashes, your eyebrows also protect you from dust and diri. They trop dust and diri and prevent them from entering your eyes. Eyebrows also od as one of your most expressive facial features. They help you to determine how people are feeling. If a person raises his/her eyebrows, chances are that he/she is surprised a bit.


The amount of sleep an individual requires varies from person person. On average, most adults need eight hours of sleep. Sleep
plays an important role in our daily routine. During this inactive period, the body recharges the weary organs and tissues and brings back the energy required to start working effectively. The lifestyle of an individual is another factor in the amount of time he/she needs to regain his/her healthy balance and to feel fresh after he/she has got up. The quality of an individual’s sleep is also another factor which determines the amount of sleep. The body rests during sleep. However, the brain remains active, gets “recharged” and still controls many bodily functions including breathing. Just like any other characteristics you are born with, the amount of sleep you need to function best may be different for you than for someone who is of the same age and gender. While you may be at your absolute best sleeping seven hours a night, someone else may clearly need nine hours to have a happy, productive life.


cases of chronic bad breath originate in to the most current esearch, over 90 per cent of all the the mouth, not in the stomach, sinuses or lungs. All the cases of bad breath are caused by Volatile Sulphur Compounds ISCs). One compound is hydrogen sulphide (the rotten smell of an egg) and another is methyl mercaptan (the essence of skunk oil). The source of these compounds is bacteria in the mouth which break down the cell wall of dead cells. These anaerobic bacteria collect and multiply, mainly on the tongue. They thrive in a dry, dark environment such as under the gums, the spaces between the teeth and the crevices of the tongue. The diet of an individual can cause bad breath because certain foods increase the quantity of anaerobic bacteria that produce VSCs. It is believed that dieting can also cause bad breath.


The unnerving, tingling sensation a person feels when his/her body part “falls asleep is actually the result of example, when a person nerves under pressure. For sleeps in one position for a long time, his/her arm may fall asleep. This happens because the
sleeping position exeris pressure on the nerves. As a result, the nerves carry the inhibited messages to the brain and to the rest of the body. At the same time, it also squeezes the blood vessels due to which the oxygen carried by these nerves never reaches its destination. When the sleeping position is changed, pressure from these nerves and blood vessels is released. The nerve fibres awaken in order of their thickness, the thickest ones awaken the last. This awakening process causes the different sensations (first tingling and then burning) a person experiences, as his/her affected body parts return to normal.


hears a popping sound coming from the knee joints. Similarly, when When a person does a deep knee bend, it is very likely that he/she he/she cracks his/her knuckles, he/she can also hear the popping sound. The question arises as to how we hear these popping sounds The sound heard when a person does a deep knee bend is actually a snapping sound produced when his/her tendons (fibres that connect muscles and bones) elastically snap into new positions. As a result, his/her joints move under stress. Due to this back-and- forth movement of the tendon with the joint, he/she is able to hear the popping sound. Similarly, the sound heard, when a person’s knuckles crack, results when a finger joint is extended almost to the end of its range. The joint, surrounded by a lubricating fluid, is encased in a capsule. The gas dissolved in the fluid separates from the solution and forms a small bubble. Thus, it makes a cracking sound.


There are approximately 60 to 100 trillion cells in the body. A ell is one of the most basic units of life. It has a skin, wastes into and out of the cell. Inside called the plasma membrane which protects it from the outside environment. The cell membrane regulates the move. ment of water nutrients and the cell membrane are the working parts of the cell. At the centre of the cell is the nucleus. The nucleus contains the DNA, the genetic code that co-ordinates protein synthesis. Besides, there are many organelles inside the cell — small structures that help carry out the day- to-day operations of the cell. One important cellular organelle is the ribosome. Ribosomes participate in protein synthesis. Another important cellular organelles are the mitochondria. They are often referred to as the power plants of the cell because many of the reactions that produce energy take place in mitochondria. Also important in the life of a cell are the lysosomes. Lysosomes are organelles that contain enzymes that aid in the digestion of nutrient molecules and other materials


The basic computational unit in the nervous system is the nerve cell or neuron. Neurons transmit electrical and chemical signals that instruct the muscles to move. Nerve cells connect to one another through the spiny passages. Each of the nerve cells has three parts. The long arms of the nerve cell are axons. The “fingers” of the axons are called dendrites. At the end of dendrites are synapses. All of these parts of the nerve cell work together to connect cells to one another. A neuron receives input from other neurons. Once the input has exceeded a critical level, the neuron discharges a spike – an electrical pulse that travels from the body, down the axon, to the next neuron(s) or other receptors. The transmission of an electrical signal from one neuron to the next is effected by neuro-transmittors, chemicals which are released from the first neuron and bind themselves to the receptors in the second neuron. This link is called a synapse. The extent to which the signal from one neuron is passed on to the next depends on many factors, e.g. the amount of neurotransmittor available, the number and arrange- ment of receptors, amount of neuro-transmittor reabsorbed etc.


The muscles which make up the heart are known as the cardio muscles. The cardiac muscles are found only in the heart. These consist of a network of the branches of muscle fibres which have a striped appearance. The cardiac muscles are involuntary in nature, which means that they are not under the control of the central nervous system, A contraction of the heart muscle originates an electrical impulse in a natural pacemaker called the sinod- rol node, which is located inside the heart. This sinoatrial node determines both the rhythm and rate of the heart. This node sends out regular electrical impulses to produce orderly contraction of the hean chambers. This, in turn, activates the sympathetic and parasympathetic nerves to increase or decrease the heart rate. A cardiac muscle is myogenic, meaning that it is self- excitable. It simulates contraction without a requisite electrical impulse coming from the central nervous system,


Actually the funny bone has nothing to do with laughter. In act, it isn’t even a bone at all, It is really a nerve called the ulnar nerve. It runs right next to the “humerus’. That’s where the funny bone comes from When you bend your elbow, you have this ulnar nerver that is much easier to get to than most nerves are. So, when you hit your elbow, the nerve also gets whacked and begins to send messages that travel all the way up your arm to your spinal cord and along your spinal cord to your brain. It results in a tingling sensa-tion that shoots from your elbow, where the impact occurred to the tip of your little finger which is where the nerve ends.


The oppendix is a tube, one end of which is closed and the other opens into the cecum, which is the beginning of the large intestine. The appendix has no known function in o human. Evidence suggests that our evolutionary ancestors used their appendixes to digest tough food like free barks, but we don’t use ours in digestion now. It is believed that the appendix will
gradually disappear in a human being as our diet does not include cellulose any more. In the other animals, the appendix is much larger and provides a pouch off the main intestinal tract in which cellulose can be trapped and be subjected to prolonged digestion. Indigestible food delivered from the small intestine to the large intestine flows into the appendix and is
forced out by the contraction of the muscular walls of the appendix. A blockage in the opening, where the appendix attaches to the large intestine, can lead to the inflammation of the appendix, known as appendicitis. This can cause acute pain, fever, nausea, vomiting and loss of appetite. It can be ured easily by the removal of the pendix


 The seismograph is a device to record the movement and waves of the earth’s crust, especially about earth quakes and their intensities. In 132 A.D., Chang Heng of China invented a device for registering a seismic activity. The device had a number of metal balls around the rim of an um. They were patterned in such a way that an earth’s tremor would listurb a central column, working a mechanism that dropped one of its balls into a metal holder causing a noise. The directions of the earthquake would be worked out by seeing the balls that fell and that did not fall. Today’s modern and sensitive seismograph is a modified version of the ancient one. Today, seismic recording equipment are fixed in every country. A heavy inert weight is suspended in the instrument by a spring. Attached to this is a fixed pen that is in contact with paper on a rotating drum. The pen never moves during an earthquake. Instead, the frame and the drum of the instrument move causing the pen to record a zigzag line on the paper. * ?


 Milking machine is a gadget used for milking cows. The first milking machine was designed by an American engineer Lee Colvin in 1860. had four rubber teal cups which were connected to a vacuum chambo attached to the side of a bucket. The chamber was similari appearance to bellows, and a vacuum was made by pumping the handle after a cow’s tech slowly had been replaced by the rubber cups. It was realized that continuous Suction was painful to the cow and often caused internal bleeding. lis improved version was pro duced by Dr. Alexander Sheelds of Glasgow in 1895, but this model was pretty costly for the farmers. The modern carousel milking machine consists of a large slow moving platform powered by an electric motor with space for several cows. As cows approach the platform, they are placed at their own feeders and a milking machine helps produce milk, which is collected in glass containers A2


The earliest known written reference to an artificial limb was made around 500 B.C. Herodotus wrote of a prisoner who escaped from his chains by cutting off his foot. He later replaced it with a wooden substitute. An artificial limb dating from 300 B.C. was a copper and wood leg unearthed at Capri, Italy in 1858 Ambroise Pare was a very popular surgeon, largely because he introduced many improvements in the existing methods of medication. For example, he gave up the practice of healing wounds with boiling oil. Instead, he tied off the exposed arteries and covered the wound with simple dressings. Pare developed several artificial limbs such as arms and hands. He made an arm that could be bent at the elbow and a hand with movable fingers. Even today, Pare is considered to be the first person to have devised artificial limbs. He used springs and cogs to move artificial arms and legs. Today whole legs and arms can be replaced with computer controlled plastic or metal limbs. In some cases, nerve endings in the patient’s limb send messages to motors in the artificial limb to make it move.


 A microscope is a device through which an object seems larger and is brought nearer to the human eye. The microscope was invented some time between 1590 and 1610. No one is quite sure who really did it, but the credit is normally given to Galileo. A Dutch scientist, named Leeuwenhoek, is sometimes known as the father of microscope’, but that’s because of the several discoveries he made with the microscope. In the microscope, magnification occurs in two stages. There is a lens known as the objective which produces a basic magnified image. Then, there is another lens known as ‘the eyepiece or ‘ocular’ which magnifies the first image. Leeuwenhoek was the first to have seen the microscopic forms of life like protozod and bacteria With his own microscope he was the first to have seen the entire circulation of blood.


 Leonardo da Vinci, an Italian artist and inventor, sketched a simple helicopter about 500 years ago, but it was never built . It was Paul Comu and a French inventor who really built the first helicopter in 1907. rose to a height of 30 cm and ZETELN hovered there for 20 seconds. The helicopter built by Cornu was very difficult to control. It was only in the 1930s that helicopters became a practical means of flying. Helicopters have one or two large rotors made up of long, thin wings. When the rotors spin rotate, they lift the aircraft and drive it along. They can fly forwards, backwards and sideways. The first single blade helicopter was built in 1939 by a Russian American Skorsky.


 Prehistoric people had to travel everywhere carrying their goods or dragging them on sledges. By 3,000 BC, people had developed wheeled vehicles pulled by animals. It was only in the late 1800s that the invention of steam engine ond petrol engine changed land travel. The maiden land vehicle that was self-propelled with an engine was made in 1769 by a Frenchman, Nicholas Cugnot. It was o cumbersome three-wheeled can with a steam engine and o massive boiler. The first vehicle to be powered by a petrol engine was built by a German engineer, Karl Benz in 1885. The first petrol-powered car was developed in 1886 by another German, Gottlieb Daimler. In the United States, two brothers Frank and Charles Dauryea made the first successful American petrol auto- mobile in 1892


 No single person can be crowned for the invention of the elevator. Its development is a result of combined efforts made by several people. The practice of lifting loads by mechanical means during construction goes back to Roman times. The Roman architect engineer Vitruvius Pollio in the 19 century BC designed lifting platforms that used pulleys operated by humans, animals or powered by water. In 1800 AD in England, steam power began to be used to operate such devices. In the early 19 century, hydraulic lift was introduced for the first time. In 1853, Elisha Graves Otis introduced a safety device and the first passenger elevator came into being. This was put into working in the Haughwout Department Store in New York City in 1857. It was powered by steam. It used to climb five floors in less than a minute. Finally, in 1984, the field of elevators saw a major breakthrough with the introduction of push buttons. X A7


  Hang gliden in depend on the wind and warm air to fly British engine George Coyle was the first design a suitably shaped wing Many consider him the first true scientific aerial investigator and the first person to understand the underlying principles and forces of flight. He built his first serial device in 1796, a model helicopter with contro-rotating propellers. But it was oHo Lilienthal who made the first flight in which the pilot controlled the machine. He died in 1896 when his hang glider crashed. In September 1900 at kill Devil Hills near Kitty Hawk, Wilbur Wright and Orville Wright were testing their own gliders. In 1902, they executed almost 1,000 glides in o glider. In 1903, they built a 3,337 kg machine with a 12 hp motor. Finally on 17″ December 1903, Orville Wright made the world’s first powered ilight. Flyer 1 flew for 12 seconds and covered 37 metres. Wilbur flew for 270 metres and was in the air for o minute. Thus, the Wright brothers flew the first engine powered aeroplane. ory.


Metal pans filled with charcoal were used for smoothing fabrics in China in the 1st century BC. From the 17th century, the thick slabs of cast iron (delta-shaped) with handles were heated in a fire. In the late nineteenth and early twentieth centuries, there were many irons in use which were heated by a fuel such as kerosene, alcohol, whale oil, natural gas, carbide gas (acetylene) or even gasoline. In 1882, an American Henry Seely made the first working electric iron. It was only in 1885 that it was sold. The electric iron, uses resistive heating from an electric current. The hot plate, called the sole plate, is made of aluminium or stainless steel. The heating element is controlled by a thermostat which switches the current on and off to maintain the selected temperature. A steam iron gives heat and steam simultaneously for ironing several different fabrics. It has a water tank in which water is boiled by the heating element to produce steam. A push button on the top of the iron opens a valve to let the steam in through the holes on the clothes being ironed. Steam makes the clothes slightly moist which adds to remove wrinkles, because moisture softens the fibres in the material and thus makes them flexible.


 In order to keep food cool, ancient people stored them in ice pits. THE was done about 4,000 years ago. Insulated cabinets for keeping ice or, in other words, domestic refrigerators first came into existence around 1850 in the United States. In 1879, o German engineer Karl von Linde developed the first mechanical refrigerator which was powered by a steam pump. Within 12 years about 12,000 refrigerators were sold in Germany and the United States. Two Swedish engineers, Von Platen and Munters developed the first electrical refrigerator which went on sale in 1925. The main principle on which a refrigerator works is compression and absorption Compression and absorption systems cool by altering a refrigerant from o liquid state to o gaseous state ond back into the liquid form. The refrigerator has a storage tank filled with freon gas, the refrigerant control device, the evaporator, compressor and condenser SO


   According to a Chinese legend, the discovery of silk has been credited to Hsi-ling-shi, the 14-year old bride of Emperor Huang Ti in the garden of Emperor Huangti. Upon the request of her husband, Hsi-ling-shi searched for the reason which was damaging the Emperor’s fine Mulberry trees and discovered caterpillars ferociously devouring the leaves and building their cocoons. In order to destroy the source of the problem, she puta cocoon into hot water. To her surprise, she found that a delicate, single thread unwound itself-thus silk was discovered. Silk was discovered by the Chinese over 4,600 years ago. They set up farms to breed silkworms about 3,500 years ago but did not reveal the secret for another 2,000 years. It was usually the caterpillar of a moth which spins a cocoon around itself. The caterpillar feeds on the leaves of the mulberry tree. Silk was so valuable that the Chinese traded it for gold and silver. The trade route that connected China with the rest was called the Silk Road’. It was named so because of the most valuable material silk, which was carried along it. As silk was so rare, they charged a high price for it. The price kept on increasing as the cloth passed from merchant to merchant along the Silk Road


 Iron contains a lot of carbon. That is why iron products break som carbon is removed, iron becomes a solid metal called steel Steel fiest developed over 3,000 years ago. Stoel is used in making railway lines, knives and many more Bessemer’s interest in steel com from an idea he had during Crimean War to make a new lype artillery. Existing cannons were not strong enough. So, he thought Bessemer converter, which allowed unskilled improve the cannons by strengthening steel. In doing so, he created the idea for the workers to make vast quantities of quality ste cheaply. An egg-shaped vat held molten iron, and cold air was blown into perforations in the bottom to remove the carbon and other impurities in the iron. The process only took 20 minutes and raised annual steel production enormously while reducing cost dramatically Most of the carbon in the iron was burned, turning it into steel. Iron and steel objects rust in damp air. When iron comes in contact with moisture, i turns into iron oxide. In order to make steel rust-resistant, Briton Harry added chromium to steel. Thus in 1913, the first successful rust-resistant stainless steel was produced


Most plastics are made up of small, carbon- based molecules called monomers. These molecules are joined together to form long chains called polymers. The long chains tangle together like a ball of string, giving plastic its familiar strength. Many plastics are made from liquids and gases that are extracted from crude oil. Plastics like poly vinyl chloride, polythene, nylon and some paints are made from chemicals Found in oil, natural gas or coal. Polythene was discovered by ccident in 1933 by chemists working in ICl in Britain. Two years later, nylon was made by Wallace Grothers in the United States. The world’s first artificial plastic was called Bakelite. It was made in 1909 by a Belgian- American chemist Leo Hendrik Baekeland. As it did not conduct heat or electricity, it was ideal for making electrical goods. Fibreglass material is made by mixing glass fibres and plastic. It is flame resistant, does not rust and is tough enough to make the boats or the bodies of cars. This plastic was developed in the 1930s in the United States.


Am com isso fimy pomide which fogement meae SUDSONDE elements are more on pratos COTO DOS charge. Te charge and candle the museus Ernier in the 18905, scientists through cons Sondlike biliard bolso completely unbreakable le 1897, Thomson discovered to con contained er smalle prices which he called electrons. In 1908 Ruthe old discovered derse nudeus at its centre. In 1932, lone Chedwick found that the nudes contained two kinds of panic orotons and refrons. In the some year, British sciemissjon Cook and Emes Wation Firsi spin the sun which releosed huge amount of energy Holion bom Enrico Fermi om his team built the first success nucleor reodior to control this energy in the year 1942. The first nuce power siction was opened in Russian yeor 195


 Coal, oil and gas are called fossil fuels. Coal is actually the remains of ancient plants that lived and died in the prehistoric forests. The first coal fired power station to generate electricity was opened in 1882. Oil and gas are made from the bodies of tiny dead sea organisms There are three main kinds of oil – essential, fixed and mineral oils. Essential oils are thin perfumed oils from plants which are used in flavouring and aromatherapy. Fixed oils are made by plants and animals from fatty acids like fish oils and seed oils. Mineral oils come from the remains of sea organisms. Large oil deposits were found under the North Sea in the 1970s. Oil wells were drilled 200 metres beneath the sea. Offshore oil rigs were built to pump the oil to the surface.


 The Sun was man’s first clock. He guessed the time by watching the Sun as it shone across the sky. Then, there came the shadow clocks. People noticed that the shadow changed length and moved during the day. They could tell the time more accurately be watching shadows than by looking at the Sun. Sundials and shadow clocks were first used in ancient Egypt. Then, the Babylonians improved upon the sundial. They divided the circle of the sundial into 360 parts or degrees and divided it into 12 hours. In the Middle Ages, the hour or sandglass was a popular clock. The first practical clock was driven by a pendulum. It was developed by Christian Huygens around 1656. By 1690, the pendulum clock also had a minute hand. In 1969, there came the atomic clocks which were very accurate. Modern timepieces are often digital. These clocks contain electronic circuits which receive digital signals. The clocks receive the signals in binary code which it can understand


  British mathematician Charles Babbage became popular due to his invention of the first mechanical computer in 1834. He is known as the Father of Computing” for his contributions to the basic design of the computer through his Analytical machine. His previous Difference Engine was a special purpose device intended for the production of tables. Due to lack of money, he could not build his computer. Finally, in 1991, his programmed computer was made and it worked. The first proper automatic computer was built in 1945 by two Americans John Mauchly and P. Prosper Eckert Jr. It used 19,000 valves, each as big as a hand to control the switches because of which the computer become very heavy. Computers became smaller when valves were replaced by tiny transistors in the 1950s. In 1978, Steve Jobs and Steve Wozniak developed the first Successful personal computer which we use today


 WHICH INVENTOR IS RESPONSIBLE FOR John Logie Baird, a Scottish inventor, was the first to demonstrate the television in public in 1926. His original machine comprised on tea chest as a base, on which he mounted a motor and attached o home-made Nipkow disco cardboard circle cut from a hot box damning needle became a spindle and a discarded biscuit box moden were a few bull’s-eye lenses, 0 lamp housing. Apart the motor, his greatest investments purchased for four pence o piece Glued together with sealing we and string, it was a precarious contraption, but it worked. The first picture to be shown was that of a 15 year old William Taynton. His camera had a mechanical scanner with a rotating disc. This mechanical scanner was replaced by an electronic scanner developed by the American-Russian Vladimir Zworykin in 1923. The first colour television went on sale in the 1950s. Colour television cameras split the light from the scene being filmed into red, blue and green The light from each image is tumed into an electrical signal which is recorded with the sound signal on the film. A televison converts these signals back into the three images coloured picture


human develops iwe sels olleeth in his/her lilalim A116 permanent leath. A looth consists of four Windo dentine, enamel and cementum. The pulp la the story footh. Il consists ol connective issues, blood, vessels and nerves The blood vessels nourish the tooth. The hard, yellow substance which surrounds the pulp is the dentine which makes up the main part of the tooth. li is made up of mineral salts, water and living cells and is harder than bone, Above the dentine, is the enamel which is known as the crown of the tooth and is above the gum- line, The enamel is the hardest substance in the body. The cementum overlays the dentine in the root of the footh. It is a hard bony substance which is surrounded by a periodontal ligament which contains the fibres that anchor the footh in the bone of the gum,


Human beings develop two sets of teeth in their lifetime. The first seld 20 teeth are called the milk teeth or primary teeth. A baby is born with the teeth already developing in the jaws. The average age for the appearance of the first four froni teeth is 7 months. The secondary or permanent set contains 32 teeth which begin to replace the first set around the age of 7 years. There are 16 teeth in each jaw. There are different types of teeth having different shapes to carry out various jobs. The incisors, which are flat and have sharp edges for biting, are at the front of the mouth. Next to them are the canines which have sharp points to tear the food. At the back of the mouth are the molars and the premolars which only appear in the second set of teeth. These are flattened and are used to grind the food into small pieces Molars, also ready for swallowing. called wisdom teeth, develop usually in late adolescence.


The jugular veins are in the neck and drain blood from the head, brain, face and neck and convey it towards the heart. There are four jugular veins, two on each side of the neck, namely external and internal jugulars. The extemal jugulars lie close to the surface and transport blood from the outer parts of the head and neck to the head. They lie outside the sie no-cleidomastoid muscle, pass down the neck and join the subclavian vein. The internal jugulars lie deep inside and carry blood from the interior of the skull and the deeper tissues of the neck. They run down the inside of the neck outside the internal and common carotid arteries and unite with the subclavian vein to form the innominate vein. The external jugulars are much smaller as compared to the internal jugulars. Damaging a jugular vein may lead to rapid loss of blood and death if the wound is not attended immediately.


ends at the pelvis. It goes along the midline at the back. The vertebra The spine or vertebral column begins from the base of the skull and column is not straight, but curved into an S-shape when viewed from the side. The spine is divided into five regions. Ii forms the central axis of the skeleton. The I vertebral column is composed of vertebrae, discs, ligaments and muscles. The function of the spine is to provide both mobility and stability to the body. The muscles and ligamentous supporting structures of the spine enable the spine to function in an upright position, and also allow greater degrees of motion to permit the head and trunk to assume a variety of positions for various activities. Another function of the spine is to protect the spinal cord, a nervous structure which is located in a hollow canal running down the centre of the vertebral column. The spine is able to do all these functions because of its curved, segmented structure which is made up of 33 bones or vertebrae. These 33 vertebrae are separated from one another by pads of cartilage.


Blood is a suspension of red and white blood cells, plaleleis, proteins and chemicals in a yellow-coloured fluid called plasma. Blood transports oxygen and other essential nutrients from the lungs and digestive tract to all parts of the body. Red blood cells are red only because they contain a protein-chemical called hemoglobin which is bright red in colour. Hemoglobin contains the element iron, making it an excellent vehicle for transporting oxygen and carbon dioxide. As blood passes through the lungs, oxygen molecules attach to the hemoglobin. As blood passes through the tissue of the body, the hemoglobin releases the oxygen to the cells. The empty hemoglobin molecules, then, bond with the carbon dioxide of the tissue or other waste gas, transporting it away. The life of blood cells is just for about four months. Afterwards, they start to break up. New red cells are immediately formed to replace the worn-out cells.

Human Body


  Breathing is a means by which a person absorbs oxygen from the surrounding atmosphere and exhales carbon dioxide from the blood stream through the lungs into the air . When a person breathes in, the intercostal muscles move his/her ribs upwards and downwards and the diaphragm pushes downwards, The diaphragm is a muscular layer which separates the chest cavity from the abdominal cavity. It is attached at the back to the spine and to the ribs along the side of the chest. When the diaphragm is pushed downwards, air is drawn into the lungs. To reach the lungs, air flows through the mouth or nose, then through the trachea or the windpipe which is a tube beginning at the lower end of the voice box. From the trachea, the air passes into other tubes called the bronchi, which lead into the lungs, LIK

Human Body


  The trachea or the windpipe branches at its lower end into two large air tubes called the bronchus. The right primary bronchus leads into the right lung and the left primary bronchus leads into the left lung. The outer wall of each bronchus is supported by cartilage. At the inside, the bronchus is lined with mucous membrane and many microscopic hair-like projections called cilia. These hair-like projections shift the trapped dust particles upwards. The primary bronchus, then, branch into smaller or secondary bronchi at the entrance o the lung. There are three branch entering the right lung and two in the left. Each secondary bronchus divide into smaller bronchi. These further divide into hair-like terminal bronchiole which end at microscopic bubble known as alveoli, the place wher- exchange of gases takes place. A these branching air-passages ar referred to as the bronchial tree.

Human Body


  A bone is the rigid, calcified tissue which makes up the body. Bones support the body and provide an attachment for the muscles. An adult bone consists of densely packed rod-shaped units called osteons. This composition is also called the Haversian system, as all these units are aligned in the same way. A bone is made up of different layers. The outermost layer is the periosteum, which is a thin fibrous mem- brane. This membrane covers the surface of the bone. Beneath this is the compact or cortical bone which surrounds the spongy bone. This bony tissue which looks like a sponge forms the bulk of the bone. It has gaps and spaces and is much lighter than the outer compact bone. These spaces are filled with blood vessels and jelly-like bone marrow. Blood cells are produced in this bone marrow. The major components of bone include the mineral salts, mainly calcium phosphate, which provides hardness and collagen fibres. These fibres provide strength.

Human Body


The connective tissue is spread all over the body. The main function of the connective tissue is to bind, support and provide strength to other organs and tissues of the body. The connective tissue consists of cells bound together and protein fibres in a medium called ground substance’. The ground substance can be fluid, gelor solid and is secreled by the cells of the connective tissue, The fibres provide support and strength along with flexibility There are various forms of connective tissues, but all of them are made up of salts, water, protein and carbohydrates. Inside this jelly-like connective tissue are elastic threads to give elasticity, collagen to give strength, reticulin to give support, white cells and macrophages to fight infection, fat cells for storage and plasma cells to produce antibodies. There are five main types of connective tissues – loose connective tissue, dense connective tissue, cartilage, bone and blood.

Human Body

It plants, animals or human beings. Each person is made up of?

Cells are the basic structural units that make up all living organise than a million cells. The cell is the functional unit of all tissues performs all the essential functions. Cells combine to make tissue cells may be oval, spherical, flat or elongated in shape. Each cell is surrounded by tissues into organs. The a soft and elastic membrane known as plasma membrane. The cell membrane is filled with a semi transparent jelly-like fluid known as cytoplasm. This fluid contains important structural units called organelles. These organelles are concerned with the manufacture protein, generation of energy, cell division and all other functions. nucleus which contains genetic information in the form of DNA, controls the functions of the cells.

Human Body


  The eye is a very complex and delicate structure through which we can see. The eye can be compared to a camera. It has an adjustable opening to let in the light. This opening is called the pupil. It has a lens which focuses light to form an image and the relina where the image is Tormed Light enters the eye through the come a, which is a transparent dome on the surface of the eye. Through the cornea, light enters the pupil of the eye. Light reaches the retina after passing through the optic lens and vitreous humour. The retina contains light sensitive cells called rods and cones, whose main function is to perceive light intensity. The retina has photoreceptors which send visual information to the brain. The optic nerve connects the eye to the brain.



  There are two kidneys in a human body. They lie at the back, one either side of the backbone. They look like reddish brown beans and are each about the size of a clenched fist. The nutrients and oxygen we take in is ‘burned to make energy for life to continue. This ‘burning’ process which takes place in our body cells also creates waste products which must be removed. The removal of waste products is termed as excretion and it is the kidneys which perform this function. Kidneys clean the blood by filtering out waste materials and straining off any water which the body does not require. Waste materials pass out through the water into the bladder, from where it is discharged from the body in the form of urine. Another function of the kidneys is to produce hormones which help regulate the blood pressure.

Human Body


 The retina is the light sensitive layer of the rear inner surore eyeball Light reaches the resineter passing through the the lens. When light reaches the retina, it is converted signals by specialized coils called photoreceptors. Based shape, they are classified into two types: rods and cones. Rod photo receptors are more sensitive to light. These are connected together. Then, the sum of signals is sent to the brain. They are good for sensing brightness and movement rather than detailed vision There are about 125 million rod cells. The cone receptors are not as sensitive to light as the rods, but they can detect colours. Cone cells are responsible for detailed vision There are about 7 million cone cells.

Human Body


The heart is a muscular organ which pumps blood around the body. It is made up of two halves seporated by a thick muscular wall . Each half is further lder divided into an upper and o | lower chamber . Thus, the heart has four chambers, namely a left and a night atrium ond o left and o right ventricle. Blood rich in oxygen from the lungs flows into the left atrium and is forced through a valve into the lett ventricle. From there, the blood is pumped out into the aorta which is the largest artery of the body. Finally, the blood goes to the rest of the body. Deoxygenated blood or blood carrying waste products from all over the body goes into the right atrium and then the right ventricle. From there, the blood is pumped towards the lungs for exchange of gases to take place. In the lungs, the blood of carbon dioxide and takes gets rid oxygen, ready to go back to the heart. Then, the same process is repeated.

Human Body


 The immune system is a complex network of organs, cells and proteins whose fonction is to protect the body from ciseases. It is due to this sstem that we say that the body is capable of protecting itself from the invasion of disease-causing microbes. The immune system is scattered all over the body White blood cells, called lymphocytes, are stored in the lymphatic or immune system of the body. This system is actually a network of thin tubes carrying a watery fluid called lymph. At the end of the lymph are small lumps, colled lymph nodes, where lymphocytes are stored. Lymph nodes filter out and destroy foreign bodies before they get into circulation. They also activate the lymphocytes to produce certain antibodies, which proteci and repair the damaged

Human Body


 The skin is the outer waterproof covening of the body. The skin the body from extemal agents, extremes of temperature, viruses bacteria and parasites. It contains nerves which respond to pain, touch layers, namely the outer protes and temperature. The skin is made up of two layer called the epidermis and the inner loyer called the dermis. The epidermis is the skin a person sees on his/her body. It is made of dead cells. The epidermis consists of five sub-layers As cells in the top layer die, they are replaced by new cells from the lower layers. It takes about four weeks for cells , formed at the bottom layer , to reach and replace those in the top layer. The inner layer , the dermis, con- tains a network of blood vessels, nerves and fat lobules. The dermis is a network of protein fibres and elastin which provide strength and support to the skin.

Human Body


The ear is made up of three parts, namely the outerear, the middle ed and the inner ear. The inner ear contains a structure called th cochlea, which is a small, spiral-shaped structure. It contains fluid an special hair that serve as sound sensors. The vibrations of the membrane covering the oval window cause woves to form in the cochlear fluid. These vibrations are picked up by the organ of Corti, which is the hearing organ situated in the cochlea. The organ of corti consists of the rows of cells with fine hair-like projections under a layer of membrane. The movement of the hair provides the brain with information on the volume or intensity of sound. So sounds stimulate only a few cells whereas loud sounds stimulate man cells. When vibrations in the flui reach them, the nerve endings fire o electrical impulses which are ser along the nerve to the brain to b interpreted as sounds.

Human Body


attaches a muscle to a bone. It is similor in A lendon is a glistening white cord of the connective tissue structure to a ligament , which connects a bone to lo bone. The tendons play a very crucial role in the movement of the human body by the force created by muscles to move bones. In this way, they allow muscles to control movement from a distance. Tendons transmitting are tough, fibrous and flexible. They are, however, not elastic. Tendons are made up of collagen fibres, ground substances and cells, which are referred to as fibrocytes in tendons. At the point where a tendon touches a bone, the 1 tendon fibres gradually pass into the substance of the bone and meld with it. Some tendons run inside a fibrous sheath. Between the sheath and the tendon is a thin film of lubricant called synovial fluid. This he tendons to glide smoothly Over surrounding parts.

Human Body


  There are about 600 major muscles in the human body. All the   movements made by the human body ore the   result of the action of the muscles. There   are three types of muscles – skeletal   muscles, smooth muscles and cardiac   muscles. Skeletal muscles hold the   bones of the body and give shape to   the body. They make a large part of   the chest, neck, face, arms and   abdomen. Smooth muscles are   found in the walls of stomach,   intestines, blood vessels and bladder.   Cardiac muscles have the characteristics   of both skeletal and smooth muscles.   These muscles are found only in the heart.   When the cardiac muscles contract, blood is   pushed out of the heart and passes   into the arteries. Muscles are also   voluntary, whereas involuntary in   nature. Voluntary muscles are those   over which we have control, whereas   involuntary muscles are those which   operate automatically.

Human Body


   Tears are produced by the lacrimal   glands in the eyes. A lacrimal gland is   situated in the upper outer corner of   each orbit behind the eyelid. Tears   constantly wet the tough outer layer   of the eyeball, called the cornea. The   most important function of the tears   is to keep away foreign particles, like   dust and hair. The fluid produced by   the lacrimal gland is a salty solution,   which contains certain substances. It   helps to fight bacteria, protect the   eyes from infection. This fluid is   passed through several small glands   ituated in the underside of the   yelid. Each time a person blinks, the fluid from the glands is sucked by   ne eyelid. There are three types of tears :-   1.   Basal tears – In healthy   mammalian eyes, the cornea is   continually kept wet and   nourished by basal tears.   2. Reflex teras – These tears result   from the irritation of the eye by   foreign particles, such as onion   vapour, tear gas or pepper   spray   These reflex tears attempt   to wash out irritants that may have   come into contact with the eyes.   3.   Psychic tears – These tears are   caused due to strong   emotional stress, depression or   physical pain.

Human Body


 The circulation system of o human   body is very efficient. It has a very   complex and delicate system   of blood vessels carrying   blood to and from the heon   This system is carried out   with the help of arteries,   veins and capillaries. The   orteries are blood vessels   which carry purified blood   from the heart to the   various parts of the body   The blood is pushed out of the   heart to the arteries under high   pressure. Therefore, the arieries have   thick and muscular walls. Veins bring   back blood from all the parts of the   body containing waste products. Here   the pressure is low, so the walls are   thinner in comparison to the arteries,   Hence, we see that the heart is the   purifying station. Capillaries are very   narrow blood vessels which transfer   blood from the arteries to the veins.   The capillaries are about one-tenth the   thickness of a human hair. This is how   blood is circulated in the body.

Human Body


 The ear is comprised of three portions, namely the   outer ear, the middle ear and the inner ear. The   funnel-shaped outer ear collects sound waves which   travel down a canal. At the   end of this canal, there   is a thin membrane   known as the eardrum.   This membrane   separates the outer   ear from the inner   ear. There are three   small bones in the middle ear – the   hammer, the anvil and the stirrup. When   sound waves strike the membrane, it causes the three   bones to vibrate. This vibration, in turn, makes the liquid in the snail.   shaped chamber or the inner ear to vibrate. In the inner ear, there is   located cochlea or various responsive hair cells which transfer the   sound to the nerves which, in turn,   send them to the brain. The brain,   then, recognizes these messages. This  recognition is known as hearing.

Human Body


   The brain is the most crucial port of   human body. It is also called the   regulator of the body. It is the   main port of the nervous system   It receives messages from the   nervous system, sends   instruction to the muscles and   regulates all the functions of   the body. The human brain is   divided into three main regions:   cerebrum, cerebellum and   medulla. The cerebrum is the   largest part of the brain. It controls   thinking, reasoning and memory.   The cerebellum is the second largest   part of the brain. It co-ordinates the   movement and balance of the body. The medulla or the brain stem is a   small region at the base which controls   and processes the involuntary activities   like breathing, heartbeat, digestion   and growth of the body. It is interesting   to note that each side of the brain   controls the opposite side of the body.

Human Body


   The central nervous system is comprised of   the brain and the spinal cord. The spinal   cord is made up of a bundle of nerves.   From the spinal cord, millions of nerves   go to all the parts of the body to form   the outer nervous system. The main   function of the nerves is to transmit   messages to and from the brain.   These messages are transmitted   at a speed of about 320 km   per hour. The nerve cells are linked   together by chains so that they may   reach all the parts of the body.   Messages are transmitted along the nerves   and then chemically despatched   from one nerve cell to another. The   cerebrum which is the largest part of the   brain sorts out and responds to the   messages sent to it. It also stores   information as memory. Hence, we see   that the nerves of the spinal cord carry   messages to the brain which after   responding to them sends back these   messages through the nerves. The   human nervous system comprises about   13 billion nerve cells, out of which 10   billion are in the brain.

Human Body


 Digestion is the process which changes the food we   eat into molecules that can be obsorbed by the   blood to be carried oround the body. The food   which is taken in through the mouth is first ground   into small pieces by the teeth. The glands in the   mouth secrete a digestive juice called saliva which mixes   with the food we eat. Then, the food is passed through o   tube called the oesophagus to the stomach. The   oesophagus is about 25-30cm long. The whole   digestive system is around 9 meters long, con take   10 to 20 hours to pass through it. Here, the food is   further broken down. After which, the processed   food goes into the small intestine. Bile and other   juices cause further digestion to take place. The   digested   material, then,   passes to the   ileum where it is   absorbed by the blood. The   undigested food goes to the large  intesline. Here, water is absorbed   and the contents get solidified so that   they may be thrown out of the the body   as waste material. A human stomach   is required to produce a new layer of   mucus every two weeks, otherwise it   will digest itself.

Human Body


  Iron is one of the most common metals   on the Earth and it is present as   mineral in any ores in rocks. His   also required by many life-processes   in animals and plants. Iron forms an   important part of many proteins and   enzymes that help the human body   function efficiently. It is a component   of haemoglobin, the protein involved   in the movement of oxygen around   the body. It is also required for the   control of the cycle of cell division   and growth and for cell differentiation. Almost two-thirds of iron in the   human body forms the co-factor in haemoglobin. If the body does not   absorb enough iron in the diet, the ability of the body to transport oxygen   is affected. Iron deficiency can lead to tiredness, dizziness, fainting,   pale skin and an overall lack of   energy   It also decreases the ability of   the immune system to fight infection.   Iron also forms part of another protein   called myoglobin, which supplies   oxygen to active muscle cells. Sources   of iron include fish, beans, spinach   and other dark green vegetables, and   dried fruits. It can also be found in   iron-fortified fruit juices and cereals.   Human beings use 20 mg of iron each   day for the production of new red   blood cells, much of which is recycled   from old red blood cells.

Human Body


   The eyeball is titled into two cavities filled with fluid. The anterior cavity   contains the aqueous humour which pro-   vides nourishment to the internal   structures of the eyeball. The   posterior cavity contains a   gel-like substance which   helps the eyeball to   maintain its   shope. Every   movement of   the eyeball involves the action   of a total of six muscles. All the   movements are, however, co-   ordinated in the brain. These muscles   work in pairs to move the eyeball. For   example, if the superior oblique   muscles rotate, the eyes move   downwards and outwards. The   inferior oblique muscles move the   eyes upwards and outwards. The   interior recti make the eyes look down   and the superior recti work to pull the   eyes back and look up. When the right   eye looks to the right, the lateral rectus   on the right side of that eye contracts   and the medial rectus on the left side   of the same eye relaxes to allow the   movement of the eyeball.

Human Body


 The nose is a part of a human body that helps a human to smell,   moisten and filter the air he/she breathes. When a person breathes in,   the tiny hair, called cilia, acts   like a mesh and filters   everything (from dusi   particles to bugs ) trying to   get into the person’s nose.   As o person breathes in, the   air passes through a cavity   behind the nose. Some of   the air particles get mixed   with a thick layer of mucus.   They then move towards o   small patch at the top known   as the olfactory epithelium.   This small area contains millions of smell receptors. These smell   receptors are sensitive to scent   molecules. The receptor cells have   sensory hair stuck out. They react with   chemicals dissolved in the mucus and   pass information along nerve fibres to   the brain. The brain, then, interprets   those molecules as the sweet flowers   or the curdled milk that the person has   held up to his/her nose to smell.   Humans can distinguish between ten   thousand different smells. The   olfactory nerve picks up the scents   from the air a person breathes and   translates them into nerve impulses or   messages.

Human Body


 The normal body temperature remains almost constant. Il requires   energy to carry on its functions   efficiently. This energy is obtained   through a process called oxidation,   which is similar to combustion.   The combustion of food generates   heat energy which is mild and has   the exact warmth required by the   body. Carbohydrates are very   essential for the body as they   provide the energy required to   keep the body warm. The temperature of the body is maintained by the   “emperature centre of the brain. This centre is comprised of three parts   a) a control centre which controls the temperature of the body; b) a   heating centre which raises the temperature of the blood when it falls,   and c) a cooling centre which cools the blood when the temperature   rises. When the temperature of blood   drops too low we shiver. Then, the   body automatically produces more   heat to control the situation.

Human Body


  At the time of birth, a baby is approximately   one foot   eight inches long. This length becomes three times till   he/she is twenty years of age. After this stage he/she does   not grow. We can say that he/she grows very slightly   There is a system of glands in a human body which   controls the growth. The endocrine glands put   hormones and other products directly into the   blood. The thyroid is at the front of the neck,   whereas the pituitary is attached to the brain.   The pituitary gland is the most important   because this is the one which stimulates a   person’s bones to grow. These glands work   of o continuous rate, otherwise we would   either have very long arms and legs or very short   ones. We continue to   grow till the age of   25, after which the   growth rate becomes   slow. The maximum   height is attained at   the age of 35 or 40,   after which it shrinks   about half an inch every ten years. This   due to the reason that the cartilages   in the joints and spinal cord start drying   up as we grow older.

Human Body


   A human heart is a muscular pump   that never stops beating. It works as   a pump pushing blood around   the body. It has its own timing   device that produces tiny   electrical signals which cause   the heart muscles to contract   rhythmically. The heart is   divided into right and left   side. Each side has an upper   and lower chamber. Between these,   there are flaps called valves that open   to let in blood from one chamber to the   other, and close to stop blood flowing   backwards. The hearibeat is actually the   sound of the valves opening and closing. When   the heart stops beating, body tissues   no longer receive fresh blood. Nor   they carry oxygen and nutrients.   Hence, life ends. An adult heart   normally beats 70 to 80 times per   minute which means that the heart   beats more than 100,000 times each   day. It is more than 36 million times a   year. A woman’s heart beats faster than   a man’s. The adult heart pumps about   5 quarts of blood each minute   approximately 2,000 gallons of blood   each day throughout the body.

Human Body


 These here to or more bones meets   coot The two bones are held together   by games Ligaments are like elastic bonds   chap the bones in ploce. A cooting of   corge covering the bone surface stops   the bones from rubbing directly against   one another. This helps the joint to   osmoothly The joint is surrounded   by cople. The space within the   on contains synovial Puid. This   ud provides nutrients to the   joint. Cortloge is produced by   the synovial membrane which   Ines the joint cavity. Joints   allow the different degrees of   the movement of bones on the   basis of their structures. The human   body has more than a hundred   joints. Some joints move in all   directions, for example the shoulder   joint or the joint at the base of the   thumb. Joints like in the elbows and   knees are those which move like   simple hinges. There is very little   movement in the joints of the spine.

Human Body


   Muscles have the property of being able to contract.   They are composed of fibres which are elongated   cells containing tiny, thread-like structures   made of complex proteins called myofibrils.   These myofibrils consist of regularly arranged   protein strands called myofilaments. The thick   myofilaments contain the protein myosin while   the thin myofilaments contain the proteins   actin, troponin and tropomysin. Thick and thin   myofilaments lie side by side with their ends   interlinked by chemical cross bridges. When   stimulated, they slide along one another, which   results in a muscle contraction. There are two main   types of muscle fibres, namely fast twitch and slow   twitch fibres. The fast twitch fibres generate more   power and contract   faster but cause   fatigue more quickly   than slow twitch   fibres. The proportion of the two type   of fibres varies in different individua   and in different muscles.

Human Body


     function of many differ   Speech depends on the   organs and structures w   the body. These can be   nervous system elements   divided into three parts: the   planning, language production   and control of muscles; 29   parts of the respiratory system   of raw sound; and 3) the   mouth area for the modification of the raw sound to produce the   vowels and consonants of speech. Within the brain, usually in the leh   and larynx for the production   hemisphere, there are two specialized language regions known as   Broca’s area and Wernicke’s area respectively. The area concerned   with the comprehension of language is known as Wernicke’s area   whereas the area involved in the expressive aspects of language is the   Broca’s area. Raw sound is produced by expelling air from the lungs   through the larynx. Within the larynx, there are two vocal cords which   can be separated during the intake of   breath and brought close together   during speech

Human Body


 three-step process. Firstly, the lungs expel air   Producing sound and turning it into speech is o   alter the air flow and cause vibrations,   Secondly, the vocal cords open and close to   making a sound. Thirdly, this sound is   modified by muscles in the mouth and   tongue involving the movement of the soft   palate, tongue and lips. The vocal cords   are the two folds of mucous membrane   that vibrate to make sound when we speak.   One end of each vocal cord is attached to the cartilage at the   front of the larynx. The other end is attached to the cartilages that can   move freely allowing the cords   to vibrate and make sound. Vowel   sounds are produced when the soft palate, tongue and lips vibrate in a   coordinated fashion. Consonants like B and P are produced by   bringing the lips together; D and T involve the tongue touching the   teeth; M and N involve possing air through the nose; Q, G and   involve the temporary closing of the   back of the tongue against the soft   palate.

Human Body


      The spinal cord is a column of nerve tissues thot   ons long te vertebral column. A fotol of 31   pois of spinel nenes make up the veries of   column. They are divided into eight cervical   spinal nenes, tuche thoracic, five lumbor, five   social and one coccygeal nerve. These spinal   nerves emerge from the sides of the verebral   column. The main function of the vertebral column   is to transmit informofion in both directions   between the spinal cord and the peripherol   structures of the body. Eoch nerve is made up of   sensory fibres and motor fibres. The sensory fibres   transmit information from the skin, muscles, bones   and joints to the spinal cord. The motor fibres   transmit messages andy from the spinal cord   towards the skeletal   muscles. Some   spinal nerves also   carry sympathetic   fibres which transmit   messages to sweat   glands and blood   vessels. Messages   travel along the   nerves as electrical   impulses. They   travel of speeds   up to 248 miles   per hour   sa .

Human Body


All living things – plants, animals or human beings – are made from cells. A cell in an individual body is too small to be seen by the naked eve. Cells are replaced automatically as soon as they die. In the 1970s, the American cellular biologist, Leonard Hayflick, discovered that most types of human cells have a natural limit to the number of times they can divide or reproduce. Some types of cells, such as those that produce red and white blood corpuscles, can divide millions of times. Others, such as most nerve cells, do not reproduce at all. Some cells have no Hayflick limit. Barring trauma from outside, they are immortal. They can be killed, but they do not age. The “lowly” bacteria are immortal. They can be killed by starvation, radiation, lack of water or being eaten by another organism. But they do not age. Bacteria keep on dividing forever, until some outside agency kills them. Similarly, cancer cells are immortal. They keep on dividing and dividing endlessly, unless they are killed or their host dies.

Human Body


  Bile is a luid which is yellow to orange in colour. It is produced by the  gallbladder is attached to the lower  hver and stored in a sac-shaped organ called the gallbladder. The  surface of the liver and lies on the  right side of the abdomen just below  the nos. The bile which is stored in  the gallbladder is, then, released  into the initial part of the small  intestine, the duodenum, for further  digestion of food to take place. Bile  contains pigments – leathin and bile  salts. The most important function of  bile when released into the small intestine is to break down large  globules of fat into smaller droplets. Thus, it provides more surface  area to the fat particles to improve their digestion and absorption,  Once the digestion and absorption of fats is complete, bile is  reabsorbed at the end of the small intestine and carried back to the  liver by a group of veins called the portal system.

Human Body


 file or hiny projections  found on the upper  surface of the longue.  The main function of  the tongue is to laste,  /chew and swallow  food. The undersurface  of the tongue is smooth  due to the mucous mem-  brone, but the upper surface  of the tongue has a rough surface due to the papillae. There are three  types of papilloe – filiform, fungiform and vallate. The filiform papillae  are tiny cone-shaped elevations, whose main function is to grip the  food. They do not have any taste buds. The fungiform papillae are  mushroom-shaped projections which often contain taste buds and  have a red appearance. The vallate papillae are V-shaped and lie  away from the tip of the tongue. They have a central elevation which is  surrounded by a deep groove. Taste  buds are located in these grooves.  There is a group of 7-12 vallates. Each  papilla contains one to two hundred  taste buds.

Human Body


   Urine is stored in a muscular sac  which resembles an inverted  pyramid known as the  bladder Urine is continuously  produced by the kidneys and stored  in the bladder. The bladder lies just  behind the pubis, one of the  bones of the pelvis. Urine is passed  from the kidneys to the bladder  through the ureters. Ureters are  wo thin muscular tubes whose walls have smooth muscles which  contract and propel urine in waves to the bladder. Urine travels from  the bladder to the outside of the body through a tube called the  urethra. The bladder can hold more than 1 litre of urine. The  emptying of the urinary bladder is voluntarily controlled in human  beings and many other mammals. The place where the bladder and  the urethra meet is called the neck of  the bladder. A complex arrangement  f muscles encircles the neck of the  ladder. This ring is called the urethral  bhincter.

Human Body


 The epiglottis is a lid-like flap of elastic cartilage tissue covered with  mucous membrane, attached to the root of the tongue. It pro  obliquely upwards behind the tongue and  the hyoid bone. The throat lies just  behind the base of the tongue. The  throat contains structures important in  breathing and eating like the pharynx,  the larynx, part of the esophagus and  part of the trachea. The epiglottis is the  flap over the opening of the voice box or  larynx and windpipe or trachea. When we  take in food, two actions take place to block  off the air passage. The soft palate presses against  the back of the pharynx, closing the opening to the  nose. At the same time, the epiglottis closes the trachea while one  swallows. Thus, it prevents the food and liquids from passing into the  trachea. These actions direct the food  to go into its own passage, the eso-  phagus. Then, muscular waves carry  the food down to the stomach.

Human Body


  The synovial joints are  found in the elbow, knuckles  and the wrist. They are the  most mobile joints of the  body as they are designed  jo allow a large range of  movements. The ends of the  bones are very smooth and  are covered with an  articular cartilage which has  very low friction Cartilage is  a tough, semuansparent,  elastic, flexihis onnective  fissue. It covers the surface of joints, allowing  the bones to slide over one another. In a synovial  joint, the two bones are bound together by a  capsule of fibrous tissue. The fibrous capsule is  lined on the inside by a synovial membrane. This  membrane secretes a fluid called the synovial  fluid which lubri  cates the joint  cartilage. The  joint is rein-  forced by tough  straps called  ligaments. Ligaments are made of the  fibres of connective tissues. They are  densely packed and run parallel in one  direction providing support to the  joints .

Human Body


 are not under the control of the central nervous system. Smooth  Smooth muscles are also known as involuntary muscles because they  muscles are found in the walls of the stomach, the intestines, the blood  vessels and the bladder. They  operate automatically and  slowly in a natural and  rhythmic manner of con-  fraction and relaxation.  Various bodily processes  are controlled in this  manner. Smooth mus-  cles are stimulated by a  special set of nerves  (that belong to the autonomic nervous system) and sy body chemicals  Autonomic nervous system is that part of the nervous system which is  concerned with controlling automatic bodily functions. Most of the  activities occur without our being aware of them. An example of the  autonomous contraction of smooth  muscles is in the stomach and the  intestines. The regular and rhythmic  contraction of the smooth muscle in  the gastrointestinal tract helps the food  to move along the gut and break it up  into a more readily digestible nutrient  This process is known as peristalsis.

Human Body


    The liver is the heaviest single organ  in a human body it is also the  largest gland and the  second largest organ in  human body. In on adult, it  weighs about three  pounds and is roughly  the size of a lootboll Its  main function is to help  the body to extract  nutrients from the blood and  store them. As a result, the  blood is cleansed of waste  products and returned to the heart,  The liver receives blood filled with oxygen from the heart. The blood  from the heart enters the liver through the hepatic artery. The blood  filled with nutrients and the digested  food particles from the small and large  intestines also enter the liver. The  portal vein is responsible for carrying  this blood. The hepatic artery and the  portal vein bronch into a network of  tiny blood vessels which emply into  sinusoids in the liver. As the blood flows  through these sinusoids, liver cells  absorb the nutrients and oxygen from  the blood. Also, the waste products are  filtered. The blood leaves the liver  through the hepatic vein.

Human Body


Sperms are the male  reproductive cells which  combine with the ovum or  the female reproductive cells.  Then, both of them lead to  the development of a baby  Sperms are produced in the  testes, the organs which  hang outside the body in a  sac of skin. Newly produced  sperms pass into a tube,  behind each testis, called  the epididymis. Here, they  mature and want to be  sperms along the sperm duct into the urethra. On the way, semina  ejaculated. During ejaculation, muscles contract, squeezing the  vesicles add seminal fluids, which mix with the sperms and mobilize  them. Sperms can live up to 72 hours in the female reproductive traci,  Sperms look like tiny tadpoles. The  acrosomal membrane which contains  head of each sperm has nucleus  containing chromosomes and an  enzymes needed for fertilization. On  an average, a male produces roughly  525 billion sperm cells over his lifetime  and sheds, at least, one billion of them  per month

Human Body


    For a body to develop Successfully  fertilization is essential Fertilization  takes place when the male reproductive organ or sperm penetrates  into the ovum, the female reproductive organ in the fallopian tube.  the ovum, called the zygote, begins  Once fertilization has taken place,  to divide itself. This developing  mass moves along the  fallopian tube and reaches  the cavity of the uterus about  78-81-8341-476.0  5-6 days after fertilization. The uterus is a hollow, muscular organ in  Whe abdomen of the female between the bladder and the recium. The  terus enlarges enormously during pregnancy. After about 10 days of  ertilization, fissues and organs begin to take shape. About two weeks  ster  , blood vessels begin to develop within the embryo. All major organ  systems are developed, although not in  functional form, by the 8th week.  External features are sufficiently  developed by the end of the eighth  week. The foetus has a recognizably  human form, including head, legs and  arms. The baby develops in the uterus  after 9 months.

Human Body


   Metacarpals are the  bones which can  be felt through the  skin over the back of  the hand. The hand  consists of the wrist  bones called carpals,  the palm bones called  metacarpals and the  finger bones called  the phalanges. Between  the wrist bones and  the finger bones, there  are five metacarpal bones. The first metacarpal between the wrist and  a wide range of movements. The fifth metacarpal is fractured  the thumb is the most mobile. That is why the thumb is able to perform  easily. Between the metacarpals and  very  the skin of the back of the hand  gre  long tendons which pull the fingers  and the thumb backwards. Each of the  four fingers has three slender bones  known as phalanges. But the thumb  has only two phalanges. The palm has  a slightly hollow surface which  provides a strong grip while holding  objects. There are 27 bones in the  hand. There are eight carpal bones in  the wrist. Five metacarpal bones make  up the palm. There are three bones in  each of the four fingers and two in the thumb.

Human Body


  Nephrons are microscopic  structures which form the  functional units of the  kidneys. The unfiltered blood  is brought to the kidneys  through the renal artery. This  artery branches into about 1  million capillaries inside  each kidney. Each capillary is  comprised of an extensive  ball-shaped capillary network  called the glomerulus. This is  surrounded by a double walled cup of epithelial tissue, also known as  Bowman’s capsule. All these structures together filter the blood. The  purified blood is returned to the body through the capillaries which join  Up into the renal vein. When the blood is filtered, a liquid called the  filtrate is produced which contains minerals, wastes and water. As this  filtrate passes along the renal tubule, a network of tiny blood vessels  (called the peritubular capillaries  reabsorbs useful substance from the  filtrate. About 99% of the filtrate  reabsorbed in this way and the rest  transported to the bladder as urine.

Human Body


   The humerus is a long bone  in the arm or forelimb. It  runs from the shoulder to  the elbow. This bone  comprises a cylindrical  shaft, a rounded head  (which forms the upper  end) and paired condyles  which form the lower end.  The upper end articulates  with the scapula or  shoulder bone to form the shoulder joint. The lower end articulates with  the radius and ulna to form the elbow joint. The joint which connects  the upper arm to the forearm is called the elbow. The elbow is also the  meeting point of the humerus, the radius and the ulna. These three  bones form three smaller joints which allow certain movements. The  humerus-ulna joint and the humerus-radius joint allow a person to  move his/her forearm up and down. The radius-ulna joint and the  humerus-radius joint permit a person to rotate his/her forearm and  turn his/her palm of the hand up and down.

Human Body


   The sacrum is a large triangular bone at the  base of the lower spine and of the upper  and back part of the pelvic cavily,  where it is inserted like a wedge  between the two hip bones. It is made  up of five fused vertebrae below the  lumbar region. Its broad upper part  joins the lowest lumbar vertebra and  its narrow lower part joins the  Coccyx or “tail bono’. The sides are  connecled to the illums (the largest  bones forming the pelvis), The sacrum is a strong bone and rarely  Fractures. The five vertebrae that make up the sacrum are separated in  early life, but gradually become fused together between the eighteenth  and thirtieth years. In a female, the sacrum is shorter and wider than in  male; the lower half forms a greater angle with the upper  The  upper  alf is nearly straight; the lower hall presents the greatest amount of  urvature. The bone is also directed more obliquely backwards this  ncreases the size of the pelvic cavity and renders the sacrovertebral  angle more prominent. In the male,  the curvature is more evenly distributed  over the whole length of the bone. It is  altogether greater than in the female,

Human Body


  The pancreas is a  fish-shaped spongy greyish.  pink organ about 6 inches (15 cm) long than  stretches across the back of the abdomen, behind  the stomach. The head of the pancreas is on the  duodenum (the first section of the small intestine)  right side of the abdomen and is connected to the  The narrow end of the  pancreas, called the tail,  extends to the left side of  the body. The pancreas is a  glandular organ that secretes  digestive enzymes internal secretions)  and hormones (external secretions). The  pancreas contains enzyme-producing  cells that secrete two hormones. The two hormones are insulin and  glucagon. Insulin and glucagon are secreted directly into the  bloodstream. Together  , they regulate the level of glucose in the blood  Insulin lowers the blood sugar level and increases the amount of  glucagon (stored carbohydrate) in the liver. Glucagon slowly increases  the blood sugar level if it falls too low. If the insulin secreting cells de  not work properly, it results ir  diabetes. The pancreas also produce  enzymes which help to digest food  and break down starches.

Human Body


   The esophagus refers to the muscular tube  with a mucus-secreting lining that leads  from the mouth via the pharynx,  down through the neck and the  Thorax, and through the  diaphragm to the stomach. In  the neck, it lies behind the air  passages – the lower end  of the larynx and the  upper part of the trachea,  In the thorax, it continues behind the trachea  and the heart and passes into the abdominal  cavity through a gap in the muscle of the  diaphragm. Less than an inch below this, it  opens into the stomach. After swallowing the  food is pushed into the top of the esophagus.  Then, it is propelled onwards by the waves of  circular muscle  relaxation below it and of contraction  above it. Then, it connects the pharynx,  which is the body cavity, common to  the digestive factory and respiratory  system with the stomach. Here, the  second stage of digestion is initiated  The esophagus is lined with the  mucous membrane and is more  deeply lined with the muscle that ac  with peristaltic action to move the  swallowed food down to the stomach

Human Body


  The eustachian tube (or auditory tube) is a tube that links the pharynx  to the middle ear. In adults, the eustachian tube is approximately 35  mm long. A portion of the tube proximal to the middle ear is made olo midole eor pressure with environmental pressure. In other words, the  bone  ; the rest is composed of cartilage. Its purpose is to equalize  eustachian tube equalizes the pressure between the middle ear and  the air outside. Normally  , the eustachian tube is closed, but it can open  to let a small amount of air through to equalize the pressure between  the middle ear and the atmosphere. When this happens, we hear a  small pop, an event familiar to aircraft  passengers or drivers in mountainous  regions. Yawning or swallowing can  pull on muscles in the neck, causing  the tube to open. Without this airway,  air would be unable to escape from  one’s ear. The middle ear would be  isolated from the atmosphere and  could be easily damaged by the changes  in atmospheric pressure.

Human Body


   The patella is a flat, triangular bone, situated on the front of the knee  the longest, most voluminous and strongest bone.  joint. It articulates with the femur (the femur is the thigh bone) which is  It covers and protects the knee joint. It is the  largest sesamoid bone in a human body. A  sesamoid bone is a bone embedded within a  tendon. It is typically found in a location  where a tendon passes over o joint, such as  the hand, knee and foot. Functionally, it acts  to protect the tendon and to increase its  mechanical effect. It is attached to the  tendon of the quadriceps femoris muscle,  which contracts to extend or straighten the  knee. The primary functional role of the patella is knee extension. The  patella increases the leverage that the tendon con exert on the femur  by increasing the angle at which it acts. The patella consists of a nearly  uniform dense cancellous tissue, covered by a thin compaci lamina.  The patella is ossified from a single centre, which usually makes its  appearance in the second or third  may be delayed until the sixth

Human Body


   The lungs contain millions olley  sacs which are located at the end  the branches of the bronchiale  These air sacs are known as avec  1 exchange between blood  and the inhaled air takes place. The  walls of the alveoli are very thinless  than a hundredth of a millimetre.  They are coated with thin-walled  capillaries filled with blood which  flows from the right side of the  heart. This blood has a high level of  carbon dioxide and a low level of  oxygen. The carbon dioxide in the  blood dittuses into the air spaces of the alveoli. Oxygen from the air  spaces goes into the blood. There are about 300 million alveoli in each  human lung. These provide a large surface area of about 1,000  square feet for the exchange of gases to take place. Oxygen which  enters the blood is bound to a protein  called haemoglobin in the red blood  cells. Haemoglobin contains a  chemical known as heme which contains  iron atoms that assist the transport of  Oxygen.

Human Body


A cough is a reflex action in order to expel anything which causes irritation to the air passages. Coughing may be due to various reasons. It may be due to minor blockages caused by the building up of mucus when we have a cold or chest infection. The delicate alveol inside the lungs may be damaged due to tobacco or smoke which blocks the alveoli and airways with thick tar. Other reasons are the polluting gases, which move about in the atmosphere from factories and vehicles. When such irritants are inhaled, they stimulate nerve receptors in the trachea and bronchi. Then, the nerve receptors send signals to the brain stem via the vagus nerve. Brain stem triggers coughing reflex via the phrenic nerve. Then, the diaphragm rises and the chest muscles contract, forcing the air out of the lungs in the form of cough.

Human Body


Perspiration is one of the ways by which a human body keeps itself at a normal temperature, which is around 98.6 degrees Fahrenheit. The body comes fully equipped with a temperature centre in the brain, which consists of a control centre, a heating centre and a cooling centre. The body uses approximately 2,500 calories of a person’s daily intake of calorie-laden food to fuel the body. This process is known as oxidation. Obviously, the body cannot tolerate this heat, which causes the temperature of the blood to rise dramatically, and the cooling centre to spring into action. The cooling centre slows the calorie-burning process and dilates or opens the blood vessels in the skin to release the excess heat. This excess heat in the form of fluid is known as perspiration. The release of this fluid cleanses the body as it pours through the pores. These pores consist of millions of tiny openings in the skin. Perspiration emerges on the surface of the skin in the form of tiny, microscopic droplets, which quickly evaporate and cool the body to its normal temperature.

Human Body


The heart is a powerful muscle which pumps blood around the body le pumps about 18,000 litres of blood around the body every day. Myocardial infarction or heart attack occurs when either or both sides of the heart is unable to pump sufficient blood to meet the needs of the body. Myocardial is the name of the muscle of the heart, while infarction means death of tissue due to insufficient blood-supply. So, myocardial infarction or heart attack is the death of heart muscle due to the loss of arterial blood supply. This usually occurs due to the blockage of the coronary arteries which supply blood to the heart. The blockage of the arteries is due to the accumulation of fatty deposits in the walls of arteries. A person who has a heart attack suffers from severe pain in the middle of the chest which possibly spreads to the left arm, neck or upper abdomen.

Human Body


The liver is an organ associated with the digestive tract. The main function of the liver is to maintain a constant concentration of glucose in the blood. The liver receives blood laden with glucose derived from the breakdown of digested food. The liver converts much of this glucose into a storage molecule called glycogen. This glycogen can be converted back to glucose for release into the blood whenever sugar is required. The inflammation of the liver or hepatitis reduces the ability of the liver to function properly. This inflammation may be caused by viruses and parasites. It may also be caused due to alcohol, certain drugs and toxic agents. There is another case in which the liver fails to function properly, which is cirrhosis of the liver. There is death of liver cells followed by the production of fibrous tissues and regeneration of liver cells in lumps or nodules. These nodules distort the normal structure of the liver and prevent the easy flow of blood through the liver. Cirrhosis is caused by excessive and prolonged consumption of alcohol.

Human Body


The partly digested food from the stomach enters the small intestine where the digestion process is completed. The food comes into contact with pancreatic juice, intestinal juice and bile and is processed further, after which the digestive process is complete. The pancreatic juice is produced by the pancreas and is brought into the small intestine via a tube or duct. The intestinal juice is produced by the small intestine and helps in the process of digestion. Bile is produced by the liver and stored in the gall bladder. It is poured into the small intestine through the bile-duct. Bile is used to break up fat globules. After all these juices have been brought into contact with food, the food is completely digested. After this, food is absorbed by tiny blood and lymph vessels in the walls of the small intestine It is, then, carried into the nourishment of the body.

Human Body


Tonsils are small masses of tissues formed under the surface lining of the mouth and throat, just behind the tongue. There are three sets of tonsils named according to their positions. The lingual tonsils lie at the base of the tongue. The palatine tonsils lie on either side of the back of the tongue and the pharyngeal tonsils or adenoids lie in the space behind the nose. The tonsils are arranged around the entrance to the respiratory and digestive tracts in order to protect the body from bacteria and viruses, which may enter through the mouth and the nose. The tonsils are part of the lymphatic system that produces special white cells called lymphocytes to fight infection. These cells are covered with a connective tissue and mucous membrane which has a number of pits. When harmful bacteria reach the throat, they are trapped in these pits and are killed.

Human Body


Mammary glands (breasts) are modified sweat glands which are present in all mammals. They are composed of cells which are capable of storing fat. Only mature females have the capacity to produce milk. During pregnancy, due to the influence of placental hormones, the amount of fat and fibrous tissue of the breasts decreases and there is increase in the amount of the glandular components. As soon as the baby is born, the pro duction of milk starts, when stimulated by certain hormones like the prolactin. Sac like structures called lobules are glands that produce milk. These lobules empty into a network of ducts or channels that transport milk from the lobules to the nipple. The release of milk from the mammary glands is controlled by another pituitary hormone called oxytocin. Breast milk is rich in lactose, protein, calcium, vitamins. It also contains antibodies that protect the baby from diseases.

Human Body


Muscles are made up of long, thin cells called muscle fibres. There are about 700 muscles in the body. But all the muscles differ in what they do and how they do. An acid called lactic acid is produced when muscles contract. This acid is like a poison in the way that it makes you feel tired. As result, it makes the muscles feel tired If the lactic acid is removed from a tired muscle, it stops feeling tired and you can do the work again with the same energy. When the muscles are active, various toxins are produced These are carried by the blood throughout the body and the body feels tired. So, feeling tired after exercise is the result of a kind of internal poisoning. However, this feeling of tiredness is essential so that the body may be given some rest. When the body rests, waste products are removed, nerve cells of the brain recharge their batteries and joints replace their supplies of lubricant which have been used up.

Human Body


A baby’s genetic make-up is decided right from the time when the egg is fertilized. The nucleus of every cell in the normal human body contains 46 chromosomes arranged as 23 pairs. At the time of fertilization, the two sex-cells fuse to from an embryo-cell with 23 pairs of chromosomes. Chromosomes are thread-like structures in the nucleus of each cell. Each parent contributes one chromosome of each pair. These chromosomes are, then, duplicated into each cell in the body. Chromosomes consist of DNA with each gene being a section of DNA that instructs the cell how to make a particular protein. Genes are nothing but units of genetic information, passed from a parent to his/her offspring and found on chromosomes in the nucleus of each cell. Every baby gets half its genes from each parent. Therefore, it inherits some of the features of both mother and father. Yet, each person has a unique genetic make-up. DNA analysis can be used for identifying individuals.

Human Body


Insulin is a hormone produced in the pancreas. The pancreas is part of the endocrine system, a network of glands which secrete various hormones into the blood to regulate the functions of the body chemically. The main purpose of insulin is to keep the level of sugar in the blood at a normal level. If insulin is produced either in high or low quantities, it can have a severe effect on the body’s metabolism. When food is digested, carbohydrates are broken down into sugars such as glucose and absorbed into the blood. If the level of sugar in blood rises, which is due to hormones like cortisone and adrenalin, insulin is released into the blood by a cluster of cells from the pancreas called Islets of Langerhans. Then, the insulin performs its function by allowing sugar to pass from the blood into the body’s cells to be used as fuel.

Human Body


Hair is a fine, thread-like structure, made of a tough protein called keratin. The base of each hair is live material, but the rest is dead. That is why when we cut our hair, we feel no pain. When we look at the skin, we feel it is smooth, but, actually, it is not so. Under microscope, we can see huge pits on the surface of the skin. These pits are called follicles, from where hair grows upwards. The shape of these pits is what makes hair straight, curly or wavy. Straight hair grows from a round follicle, wavy hair grows from an oval-shaped follicle and very curly hair grows from a flat follicle. The texture of the hair depends on the shape of the hair. A straight hair has a round shape, whereas a wavy or a curly hair is flat. Blondes have the most hair, about 1,40,000, while red head shave around 90,000 and those with black or brown hair have about 1,10,000 hairs on their heads.

Human Body


A chilli has got a molecule in it. It is called capsaicin. The capsaicin locks onto a certain channel on the surface of a nerve fibre in the mouth and all over the body. The nerve fibre signals pain. When the capsaicin molecule from the chilli locks onto that nerve fibre, it activates the nerve. The same nerve fibre also signals temperature. So, it fools the nervous system and we feel hotter than we are. This causes a heat reaction and that is why we often get red and sweaty. The reason that water doesn’t make it better is because capsaicin dissolves in oil and doesn’t mix with water. Drinking water doesn’t make any differenceas it stays locked onto the nerve cell. That is why we often desire yogurt or suchlike drinks with spicy food because they’ve got fat in them. If you want to get rid of it, you need something with some kind of fat in it. Alcohol and beer can also dissolve capsaicin and make you feel better.

Human Body


Goose bumps are a vestige from the days when humans were covered with hair. When it’s hot and we need to cool down little muscles at the base of each hair relax, our hair becomes relaxed. Our sweat glands pump out body heat in sweat. Our blood-vessels gel big to take more heat to the skin to get rid of it. When it’s cold, the arrector muscle pulls the hair up. The duct to the sweat glands gets small to conserve heat Our blood vessels also get small to save heat. Standing up of hair doesn’t make very good insulation – we don’t have enough fur for that. Humans don’t have much hair on their bodies any more. Millions of years ago, humans probably did. At that time, hair standing on end helped keep people warmer. Those little muscles we have on the end of each hair still work. They still make goose bumps. Cold is not the only thing that can cause our hair to stand on end. Fear or anger can cause the same reflex.

Human Body


The retina is a light sensitive area at the back of the eye. It has photoreceptors that send visual information to the brain via the optic nerve. Light is converted into the nerval impulses by these specialized cells called photoreceptors. These are classified into two types basedon their shapes – rods and cones These cells contain coloured substances which react when light falls on them, creating a nerve impulse. Rods are slim cells which help us to see in black and white. They work even if light is very poor. Cone cells give us colour vision. They contain various light sensitive subs tances which respond to red, yellow-green or blue-violet light. Along with the black and white images produced from the rods, the cone cells give us the coloured pictures we see. It becomes difficult for us to see colours in dim light because cones work only in bright light. There are about 125 million rod cells and 7 million cone cells in each eye.

Human Body


There are four valves within the heart. Their function is to ensure that blood flows in one direction from a atrium to a ventricle and out through its appropriate artery. There are two atrioventricular valves which are located between the atria and ventricles on each side of the heart. Between the right atrium and the right ventricle lies the tricuspid valve which consists of three triangular flaps of tissues called cusps or leaflets. The mitral or bicuspid valve is located between the left atrium and the left ventricle. The function of these two valves is to prevent backflow of blood from the ventricles to the atria during ventricular contraction. Besides these two valves, there are cardiac valves which are located at the outlets from the ventricles. The pulmonary valve is at the point where the right ventricle expels blood to the pulmonary trunk. The aortic valve lies at the outlet of the left ventricle.

Human Body


X-rays are a form of electromagnetic radiation, similar to light but of a much shorter wavelength. They can penetrate through the soft tissue such as skin and muscle. But they do not pass-through bones and other objects and hence cast denser shadows which show up as light areas on the film. X-rays are recorded by the use of photographic films. They can be used to study the internal structure of the body, especially bones. In case a person meets with an accident, he/she usually has an X-ray taken of his/her body to see if any part of the bone is broken or not. The X-rays cast shadows on the film which is coated with a sensitive emulsion on both sides. This will show the doctor whether any bone has been broken or dislocated. At the same time, excessive exposure to X-rays must be avoided because the ionizing radiations of the X-rays are harmful to tissues.

Human Body


Arteries are flexible, thick-walled, tube-shaped blood vessels that carry blood from the heart to the rest of the body. The aorta is the biggest artery in the body. It receives blood from the heart and channels it to the other major arteries of the body. The aorta arises from the left ventricle of the heart, arches upwards, backwards and to the left, then down the back of the thorax through the diaphragm and into the abdomen. Two small branches of the aorta, the coronary arteries, supply the blood to the heart muscle. From the thoracic aorta, arteries arise that supply blood to the heart, neck, head and arms. The aorta divides into two large branches in the abdomen, namely the left and right iliac. These supply blood to the pelvic region. The ilic arteries, then, continue into the legs where they are called the femoral arteries.

Human Body

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