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Yatheendradas C.k. at 04:08 PM - Mar 07, 2014 ( ) Views: 4,571

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The human body, with all its powers of endurance, its life preserving systems for combating disease and taking in nourishment, and its ability through the senses to interpret what is happening in the world outside it, is like some marvelously complex machine. 

But unlike a machine, it also has the capacity for pleasure and sensitivity to pain. And no machine, however futuristic, could match the body's ability to grow and to repair broken bones and damaged tissues, or its even more remarkable ability to maintain or multiply the human population by generating new life. 

All these powers and capacities, all the strengths and intricacies of the body, could be reduced to a few handful of chemical elements such as oxygen, hydrogen, proteins, minerals, fats, trace elements and water which are all contained in the body's cells - microscopic structures, only a few hundredths of millimeter in diameter, but with the ability to absorb nourishment, grow, excrete wastes and increase in numbers by dividing in two.

Various collections of cells make up body tissues such as skin, muscle and bone; and tissues are grouped to form organs, such as the heart, lungs and stomach. A set of organs make up a system, and the ultimate physical aim of the systems, working together, is to convert food into energy to keep the body working. 

Foodstuffs are eaten; prepared in the mouth into a form suitable for digestion; broken down in the digestive system into smaller units by the action of chemical substances called enzymes; and absorbed into the body; where they are partly used as fuel. 

For the burning of fuel in the body, as for any form of combustion, a supply of oxygen is needed. This is taken in from the lungs - a major function of the respiratory system - and distributed to the tissues by the blood, carried in the blood vessels and pumped by the heart. 

The blood vessels and the heart make up the circulatory system, which also conveys foodstuffs and waste products round the body. 

The body needs to get rid of waste products formed by the release of energy, the process known as excretion. Carbon dioxide and some water are excreted from the lungs in the air breathed out; a little water and salts are lost from the skin in sweat, and water and salts, together with complex waste products such as urea, and uric acid, are excreted from the kidneys. 

These form part of the urinary system. This also includes connecting tubes, known as the Ureters (from the kidneys to the bladder) and the urethra (from the bladder to outside the body). The bladder itself is merely a reservoir of urine. Fibrous wastes and indigestible food residues pass out of the body in the faeces. 

Some of the energy produced by the body keeps the various systems working and the rest is used for movement. This is carried out by the locomotor system, consisting of muscles, which act on the bony skeleton. The bones have an important role, not only in providing a frame work for the whole body, but also in protecting the vital organs, such as the lungs and the brain, from injury. 

Acting on information provided by the sense organs, such as the eyes and ears, the brain and the rest of the nervous system can control a variety of bodily processes, either directly or by causing various glands to release hormones- chemical messengers, which in turn act on the tissues. 

The release of the many types of hormones into the blood stream is controlled by the endocrine system, a series of glands in different parts of the body that regulate growth and the ability to reproduce. 

The body also needs to be maintained. Treatment with medicines or surgery may be required to repair the damage by injury or disease, but often the body can cope with the problem by itself. 

The body?s repair system consists of the normal continual process of replacing worn-out and damaged tissues. The ability to repair itself without outside help and the ability to grow, which is particularly obvious during childhood are two of the physical properties distinguishing the living organisms from a non-living organisms. A third is the body?s ability to perpetuate the species by reproduction - the role of the reproductive system. This involves the creation of new life by the joining of two sex cells - sperm and an egg from the parents, and the subsequent development while protected inside the mother?s body. 


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Yatheendradas C.k. at 09:21 PM - May 09, 2015 ( )

100 Fascinating Facts About The Human Body

The human body is an incredibly complex and intricate system, one that still baffles doctors and researchers on a regular basis despite thousands of years of medical knowledge. As a result, it shouldn’t be any surprise that even those body parts and functions we deal with every day have bizarre or unexpected facts and explanations behind them. From sneezes to fingernail growth, here are 100 weird, wacky, and interesting facts about the human body.

The Brain

The human brain is the most complex and least understood part of the human anatomy. There may be a lot we don’t know, but here are a few interesting facts that we’ve got covered.

  1. Nerve impulses to and from the brain travel as fast as 170 miles per hour. Ever wonder how you can react so fast to things around you or why that stubbed toe hurts right away? It’s due to the super-speedy movement of nerve impulses from your brain to the rest of your body and vice versa, bringing reactions at the speed of a high powered luxury sports car.
  2. The brain operates on the same amount of power as 10-watt light bulb. The cartoon image of a light bulb over your head when a great thought occurs isn’t too far off the mark. Your brain generates as much energy as a small light bulb even when you’re sleeping.
  3. The human brain cell can hold 5 times as much information as the Encyclopedia Britannica. Or any other encyclopedia for that matter. Scientists have yet to settle on a definitive amount, but the storage capacity of the brain in electronic terms is thought to be between 3 or even 1,000 terabytes. The National Archives of Britain, containing over 900 years of history, only takes up 70 terabytes, making your brain’s memory power pretty darn impressive.
  4. Your brain uses 20% of the oxygen that enters your bloodstream. The brain only makes up about 2% of our body mass, yet consumes more oxygen than any other organ in the body, making it extremely susceptible to damage related to oxygen deprivation. So breathe deeply to keep your brain happy and swimming in oxygenated cells.
  5. The brain is much more active at night than during the day. Logically, you would think that all the moving around, complicated calculations and tasks and general interaction we do on a daily basis during our working hours would take a lot more brain power than, say, lying in bed. Turns out, the opposite is true. When you turn off your brain turns on. Scientists don’t yet know why this is but you can thank the hard work of your brain while you sleep for all those pleasant dreams.
  6. Scientists say the higher your I.Q. the more you dream. While this may be true, don’t take it as a sign you’re mentally lacking if you can’t recall your dreams. Most of us don’t remember many of our dreams and the average length of most dreams is only 2-3 seconds–barely long enough to register.
  7. Neurons continue to grow throughout human life. For years scientists and doctors thought that brain and neural tissue couldn’t grow or regenerate. While it doesn’t act in the same manner as tissues in many other parts of the body, neurons can and do grow throughout your life, adding a whole new dimension to the study of the brain and the illnesses that affect it.
  8. Information travels at different speeds within different types of neurons. Not all neurons are the same. There are a few different types within the body and transmission along these different kinds can be as slow as 0.5 meters/sec or as fast as 120 meters/sec.
  9. The brain itself cannot feel pain. While the brain might be the pain center when you cut your finger or burn yourself, the brain itself does not have pain receptors and cannot feel pain. That doesn’t mean your head can’t hurt. The brain is surrounded by loads of tissues, nerves and blood vessels that are plenty receptive to pain and can give you a pounding headache.
  10. 80% of the brain is water. Your brain isn’t the firm, gray mass you’ve seen on TV. Living brain tissue is a squishy, pink and jelly-like organ thanks to the loads of blood and high water content of the tissue. So the next time you’re feeling dehydrated get a drink to keep your brain hydrated.

Hair and Nails

While they’re not a living part of your body, most people spend a good amount of time caring for their hair and nails. The next time you’re heading in for a haircut or manicure, think of these facts.

  1. Facial hair grows faster than any other hair on the body. If you’ve ever had a covering of stubble on your face as you’re clocking out at 5 o’clock you’re probably pretty familiar with this. In fact, if the average man never shaved his beard it would grow to over 30 feet during his lifetime, longer than a killer whale.
  2. Every day the average person loses 60-100 strands of hair. Unless you’re already bald, chances are good that you’re shedding pretty heavily on a daily basis. Your hair loss will vary in accordance with the season, pregnancy, illness, diet and age.
  3. Women’s hair is about half the diameter of men’s hair. While it might sound strange, it shouldn’t come as too much of a surprise that men’s hair should be coarser than that of women. Hair diameter also varies on average between races, making hair plugs on some men look especially obvious.
  4. One human hair can support 3.5 ounces. That’s about the weight of two full size candy bars, and with hundreds of thousands of hairs on the human head, makes the tale of Rapunzel much more plausible.
  5. The fastest growing nail is on the middle finger. And the nail on the middle finger of your dominant hand will grow the fastest of all. Why is not entirely known, but nail growth is related to the length of the finger, with the longest fingers growing nails the fastest and shortest the slowest.
  6. There are as many hairs per square inch on your body as a chimpanzee. Humans are not quite the naked apes that we’re made out to be. We have lots of hair, but on most of us it’s not obvious as a majority of the hairs are too fine or light to be seen.
  7. Blondes have more hair. They’re said to have more fun, and they definitely have more hair. Hair color determines how dense the hair on your head is. The average human has 100,000 hair follicles, each of which is capable of producing 20 individual hairs during a person’s lifetime. Blondes average 146,000 follicles while people with black hair tend to have about 110,000 follicles. Those with brown hair fit the average with 100,000 follicles and redheads have the least dense hair, with about 86,000 follicles.
  8. Fingernails grow nearly 4 times faster than toenails. If you notice that you’re trimming your fingernails much more frequently than your toenails, you’re not just imagining it. The nails that get the most exposure and are used most frequently grow the fastest. On average, nails on both the toes and fingers grow about one-tenth of an inch each month.
  9. The lifespan of a human hair is 3 to 7 years on average. While you quite a few hairs each day, your hairs actually have a pretty long life providing they aren’t subject to any trauma. Your hairs will likely get to see several different haircuts, styles, and even possibly decades before they fall out on their own.
  10. You must lose over 50% of your scalp hairs before it is apparent to anyone. You lose hundreds of hairs a day but you’ll have to lose a lot more before you or anyone else will notice. Half of the hairs on your pretty little head will have to disappear before your impending baldness will become obvious to all those around you.
  11. Human hair is virtually indestructible. Aside from its flammability, human hair decays at such a slow rate that it is practically non-disintegrative. If you’ve ever wondered how your how clogs up your pipes so quick consider this: hair cannot be destroyed by cold, change of climate, water, or other natural forces and it is resistant to many kinds of acids and corrosive chemicals.

Internal Organs

Though we may not give them much thought unless they’re bothering us, our internal organs are what allow us to go on eating, breathing and walking around. Here are some things to consider the next time you hear your stomach growl.

  1. The largest internal organ is the small intestine. Despite being called the smaller of the two intestines, your small intestine is actually four times as long as the average adult is tall. If it weren’t looped back and forth upon itself it wouldn’t fit inside the abdominal cavity.
  2. The human heart creates enough pressure to squirt blood 30 feet. No wonder you can feel your heartbeat so easily. Pumping blood through your body quickly and efficiently takes quite a bit of pressure resulting in the strong contractions of the heart and the thick walls of the ventricles which push blood to the body.
  3. The acid in your stomach is strong enough to dissolve razor blades. While you certainly shouldn’t test the fortitude of your stomach by eating a razor blade or any other metal object for that matter, the acids that digest the food you eat aren’t to be taken lightly. Hydrochloric acid, the type found in your stomach, is not only good at dissolving the pizza you had for dinner but can also eat through many types of metal.
  4. The human body is estimated to have 60,000 miles of blood vessels. To put that in perspective, the distance around the earth is about 25,000 miles, making the distance your blood vessels could travel if laid end to end more than two times around the earth.
  5. You get a new stomach lining every three to four days. The mucus-like cells lining the walls of the stomach would soon dissolve due to the strong digestive acids in your stomach if they weren’t constantly replaced. Those with ulcers know how painful it can be when stomach acid takes its toll on the lining of your stomach.
  6. The surface area of a human lung is equal to a tennis court. In order to more efficiently oxygenate the blood, the lungs are filled with thousands of branching bronchi and tiny, grape-like alveoli. These are filled with microscopic capillaries which oxygen and carbon dioxide. The large amount of surface area makes it easier for this exchange to take place, and makes sure you stay properly oxygenated at all times.
  7. Women’s hearts beat faster than men’s.The main reason for this is simply that on average women tend to be smaller than men and have less mass to pump blood to. But women’s and men’s hearts can actually act quite differently, especially when experiencing trauma like a heart attack, and many treatments that work for men must be adjusted or changed entirely to work for women.
  8. Scientists have counted over 500 different liver functions. You may not think much about your liver except after a long night of drinking, but the liver is one of the body’s hardest working, largest and busiest organs. Some of the functions your liver performs are: production of bile, decomposition of red blood cells, plasma protein synthesis, and detoxification.
  9. The aorta is nearly the diameter of a garden hose. The average adult heart is about the size of two fists, making the size of the aorta quite impressive. The artery needs to be so large as it is the main supplier of rich, oxygenated blood to the rest of the body.
  10. Your left lung is smaller than your right lung to make room for your heart. For most people, if they were asked to draw a picture of what the lungs look like they would draw both looking roughly the same size. While the lungs are fairly similar in size, the human heart, though located fairly centrally, is tilted slightly to the left making it take up more room on that side of the body and crowding out that poor left lung.
  11. You could remove a large part of your internal organs and survive. The human body may appear fragile but it’s possible to survive even with the removal of the stomach, the spleen, 75 percent of the liver, 80 percent of the intestines, one kidney, one lung, and virtually every organ from the pelvic and groin area. You might not feel too great, but the missing organs wouldn’t kill you.
  12. The adrenal glands change size throughout life. The adrenal glands, lying right above the kidneys, are responsible for releasing stress hormones like cortisol and adrenaline. In the seventh month of a fetus’ development, the glands are roughly the same size as the kidneys. At birth, the glands have shrunk slightly and will continue to do so throughout life. In fact, by the time a person reaches old age, the glands are so small they can hardly be seen.

Bodily Functions

We may not always like to talk about them, but everyone has to deal with bodily functions on a daily basis. These are a few facts about the involuntary and sometimes unpleasant actions of our bodies.

  1. Sneezes regularly exceed 100 mph. There’s a good reason why you can’t keep your eyes open when you sneeze–that sneeze is rocketing out of your body at close to 100 mph. This is, of course, a good reason to cover your mouth when you sneeze.
  2. Coughs clock in at about 60 mph. Viruses and colds get spread around the office and the classroom quickly during cold and flu season. With 60 mph coughs spraying germs far and wide, it’s no wonder.
  3. Women blink twice as many times as men do. That’s a lot of blinking every day. The average person, man or woman, blinks about 13 times a minute.
  4. A full bladder is roughly the size of a softball. No wonder you have to run to bathroom when you feel the call of the wild. The average bladder holds about 400-800 cc of fluid but most people will feel the urge to go long before that at 250 to 300 cc.
  5. Approximately 75% of human waste is made of water. While we might typically think that urine is the liquid part of human waste products, the truth is that what we consider solid waste is actually mostly water as well. You should be thankful that most waste is fairly water-filled, as drier harder stools are what cause constipation and are much harder and sometimes painful to pass.
  6. Feet have 500,000 sweat glands and can produce more than a pint of sweat a day. With that kind of sweat-producing power it’s no wonder that your gym shoes have a stench that can peel paint. Additionally, men usually have much more active sweat glands than women.
  7. During your lifetime, you will produce enough saliva to fill two swimming pools. Saliva plays an important part in beginning the digestive process and keeping the mouth lubricated, and your mouth produces quite a bit of it on a daily basis.
  8. The average person expels flatulence 14 times each day. Even if you’d like to think you’re too dignified to pass gas, the reality is that almost everyone will at least a few times a day. Digestion causes the body to release gasses which can be painful if trapped in the abdomen and not released.
  9. Earwax production is necessary for good ear health. While many people find earwax to be disgusting, it’s actually a very important part of your ear’s defense system. It protects the delicate inner ear from bacteria, fungus, dirt and even insects. It also cleans and lubricates the ear canal.

Sex and Reproduction

As taboo as it may be in some places, sex is an important part of human life as a facet of relationships and the means to reproduce. Here are a few things you might not have known.

  1. On any given day, sexual intercourse takes place 120 million times on earth. Humans are a quickly proliferating species, and with about 4% of the world’s population having sex on any given day, it’s no wonder that birth rates continue to increase in many places all over the world.
  2. The largest cell in the human body is the female egg and the smallest is the male sperm. While you can’t see skin cells or muscle cells, the ovum is typically large enough to be seen with the naked eye with a diameter of about a millimeter. The sperm cell, on the other hand, is tiny, consisting of little more than nucleus.
  3. The three things pregnant women dream most of during their first trimester are frogs, worms and potted plants. Pregnancy hormones can cause mood swings, cravings and many other unexpected changes. Oddly enough, hormones can often affect the types of dreams women have and their vividness. The most common are these three types, but many women also dream of water, giving birth or even have violent or sexually charged dreams.
  4. Your teeth start growing 6 months before you are born. While few babies are born with teeth in place, the teeth that will eventually push through the gums of young children are formed long before the child even leaves the womb. At 9 to 12 weeks the fetus starts to form the teeth buds that will turn into baby teeth.
  5. Babies are always born with blue eyes. The color of your eyes depends on the genes you get from your parents, but at birth most babies appear to have blue eyes. The reason behind this is the pigment melanin. The melanin in a newborn’s eyes often needs time after birth to be fully deposited or to be darkened by exposure to ultraviolet light, later revealing the baby’s true eye color.
  6. Babies are, pound for pound, stronger than an ox. While a baby certainly couldn’t pull a covered wagon at its present size, if the child were the size of an ox it just might very well be able to. Babies have especially strong and powerful legs for such tiny creatures, so watch out for those kicks.
  7. One out of every 2,000 newborn infants has a tooth when they are born. Nursing mothers may cringe at this fact. Sometimes the tooth is a regular baby tooth that has already erupted and sometimes it is an extra tooth that will fall out before the other set of choppers comes in.
  8. A fetus acquires fingerprints at the age of three months. When only a small fraction of the way through its development, a fetus will have already developed one of the most fascinating human traits: fingerprints. At only 6-13 weeks of development, the whorls of what will be fingerprints have already developed. Oddly enough, those fingerprints will not change throughout the person’s life and will be one of the last things to disappear after death.
  9. Every human spent about half an hour as a single cell. All life has to begin somewhere, and even the largest humans spent a short part of their lives as a single celled organism when sperm and egg cells first combine. Shortly afterward, the cells begin rapidly dividing and begin forming the components of a tiny embryo.
  10. Most men have erections every hour to hour and a half during sleep. Most people’s bodies and minds are much more active when they’re sleeping than they think. The combination of blood circulation and testosterone production can cause erections during sleep and they’re often a normal and necessary part of REM sleep.


The primary means by which we interact with the world around us is through our senses. Here are some interesting facts about these five sensory abilities.

  1. After eating too much, your hearing is less sharp. If you’re heading to a concert or a musical after a big meal you may be doing yourself a disservice. Try eating a smaller meal if you need to keep your hearing pitch perfect.
  2. About one-third of the human race has 20-20 vision. Glasses and contact wearers are hardly alone in a world where two-thirds of the population have less than perfect vision. The amount of people with perfect vision decreases further as they age.
  3. If saliva cannot dissolve something, you cannot taste it. In order for foods, or anything else, to have a taste, chemicals from the substance must be dissolved by saliva. If you don’t believe it, try drying off your tongue before tasting something.
  4. Women are born better smellers than men and remain better smellers over life. Studies have shown that women are more able to pinpoint correctly just what a smell is. Women were better able to identify citrus, vanilla, cinnamon and coffee smells. While women are overall better smellers, there is an unfortunate 2% of the population with no sense of smell at all.
  5. Your nose can remember 50,000 different scents. While a bloodhound’s nose may be a million times more sensitive than a human’s, that doesn’t mean that the human sense of smell is useless. Humans can identify a wide variety of scents and many are strongly tied to memories.
  6. Even small noises cause the pupils of the eyes to dilate. It is believed that this is why surgeons, watchmakers and others who perform delicate manual operations are so bothered by uninvited noise. The sound causes their pupils to change focus and blur their vision, making it harder to do their job well.
  7. Everyone has a unique smell, except for identical twins. Newborns are able to recognize the smell of their mothers and many of us can pinpoint the smell of our significant others and those we are close to. Part of that smell is determined by genetics, but it’s also largely due to environment, diet and personal hygiene products that create a unique chemistry for each person.

Aging and Death

From the very young to the very old, aging is a necessary and unavoidable part of life. Learn about the process with these interesting, if somewhat strange facts.

  1. The ashes of a cremated person average about 9 pounds. A big part of what gives the human body weight is the water trapped in our cells. Once cremated, that water and a majority of our tissues are destroyed, leaving little behind.

  2. Nails and hair do not continue to grow after we die. They do appear longer when we die, however, as the skin dehydrates and pulls back from the nail beds and scalp.
  3. By the age of 60, most people will have lost about half their taste buds. Perhaps you shouldn’t trust your grandma’s cooking as much as you do. Older individuals tend to lose their ability to taste, and many find that they need much more intense flavoring in order to be able to fully appreciate a dish.
  4. Your eyes are always the same size from birth but your nose and ears never stop growing. When babies look up at you with those big eyes, they’re the same size that they’ll be carrying around in their bodies for the rest of their lives. Their ears and nose, however, will grow throughout their lives and research has shown that growth peaks in seven year cycles.
  5. By 60 years of age, 60-percent of men and 40-percent of women will snore. If you’ve ever been kept awake by a snoring loved one you know the sound can be deafening. Normal snores average around 60 decibels, the noise level of normal speech, intense snores can reach more than 80 decibels, the approximate level caused by a jackhammer breaking up concrete.
  6. A baby’s head is one-quarter of it’s total length, but by age 25 will only be one-eighth of its total length. As it turns out, our adorably oversized baby heads won’t change size as drastically as the rest of our body. The legs and torso will lengthen, but the head won’t get much longer.

Disease and Injury

Most of us will get injured or sick at some point in our lives. Here are some facts on how the human body reacts to the stresses and dangers from the outside world.

  1. Monday is the day of the week when the risk of heart attack is greatest. Yet another reason to loathe Mondays! Aten year study in Scotland found that 20% more people die of heart attacks on Mondays than any other day of the week. Researchers theorize that it’s a combination of too much fun over the weekend with the stress of going back to work that causes the increase.
  2. Humans can make do longer without food than sleep. While you might feel better prepared to stay up all night partying than to give up eating, that feeling will be relatively short lived. Provided there is water, the average human could survive a month to two months without food depending on their body fat and other factors. Sleep deprived people, however, start experiencing radical personality and psychological changes after only a few sleepless days. The longest recorded time anyone has ever gone without sleep is 11 days, at the end of which the experimenter was awake, but stumbled over words, hallucinated and frequently forgot what he was doing.
  3. A simple, moderately severe sunburn damages the blood vessels extensively. How extensively? Studies have shown that it can take four to fifteen months for them to return to their normal condition. Consider that the next time you’re feeling too lazy to apply sunscreen before heading outside.
  4. Over 90% of diseases are caused or complicated by stress. That highstress job you have could be doing more than just wearing you down each day. It could also be increasing your chances of having a variety ofserious medical conditions like depression, high blood pressure and heart disease.
  5. A human head remains conscious for about 15 to 20 seconds after it is been decapitated. While it might be gross to think about, the blood in the head may be enough to keep someone alive and conscious for a few seconds after the head has been separated from the body, though reports as to the accuracy of this are widely varying.

Muscles and Bones

Muscles and Bones provide the framework for our bodies and allow us to jump, run or just lie on the couch. Here are a few facts to ponder the next time you’re lying around.

  1. It takes 17 muscles to smile and 43 to frown. Unless you’re trying to give your face a bit of a workout, smiling is a much easier option for most of us. Anyone who’s ever scowled, squinted or frowned for a long period of time knows how it tires out the face which doesn’t do a thing to improve your mood.
  2. Babies are born with 300 bones, but by adulthood the number is reduced to 206. The reason for this is that many of the bones of children are composed of smaller component bones that are not yet fused like those in the skull. This makes it easier for the baby to pass through the birth canal. The bones harden and fuse as the children grow.
  3. We are about 1 cm taller in the morning than in the evening. The cartilage between our bones gets compressed by standing, sitting and other daily activities as the day goes on, making us just a little shorter at the end of the day than at the beginning.
  4. The strongest muscle in the human body is the tongue. While you may not be able to bench press much with your tongue, it is in fact the strongest muscle in your body in proportion to its size. If you think about it, every time you eat, swallow or talk you use your tongue, ensuring it gets quite a workout throughout the day.
  5. The hardest bone in the human body is the jawbone. The next time someone suggests you take it on the chin, you might be well advised to take their advice as the jawbone is one of the most durable and hard to break bones in the body.
  6. You use 200 muscles to take one step. Depending on how you divide up muscle groups, just to take a single step you use somewhere in the neighborhood of 200 muscles. That’s a lot of work for the muscles considering most of us take about 10,000 steps a day.
  7. The tooth is the only part of the human body that can’t repair itself. If you’ve ever chipped a tooth you know just how sadly true this one is. The outer layer of the tooth is enamel which is not a living tissue. Since it’s not alive, it can’t repair itself, leaving your dentist to do the work instead.
  8. It takes twice as long to lose new muscle if you stop working out than it did to gain it. Lazy people out there shouldn’t use this as motivation to not work out, however. It’s relatively easy to build new muscle tissue and get your muscles in shape, so if anything, this fact should be motivation to get off the couch and get moving.
  9. Bone is stronger than some steel. This doesn’t mean your bones can’t break of course, as they are much less dense than steel. Bone has been found to have a tensile strength of 20,000 psi while steel is much higher at 70,000 psi. Steel is much heavier than bone, however, and pound for pound bone is the stronger material.
  10. The feet account for one quarter of all the human body’s bones. You may not give your feet much thought but they are home to more bones than any other part of your body. How many? Of the two hundred or so bones in the body, the feet contain a whopping 52 of them.

Microscopic Level

Much of what takes place in our bodies happens at a level that we simply can’t see with the naked eye. These facts will show you that sometimes that might be for the best.

  1. About 32 million bacteria call every inch of your skin home. Germaphobes don’t need to worry however, as a majority of these are entirely harmless and some are even helpful in maintaining a healthy body.
  2. Humans shed and regrow outer skin cells about every 27 days. Skin protects your delicate internal organs from the elements and as such, dries and flakes off completely about once a month so that it can maintain its strength. Chances are that last month’s skin is still hanging around your house in the form of the dust on your bookshelf or under the couch.
  3. Three hundred million cells die in the human body every minute. While that sounds like a lot, it’s really just a small fraction of the cells that are in the human body. Estimates have placed the total number of cells in the body at 10-50 trillion so you can afford to lose a few hundred million without a hitch.
  4. Humans shed about 600,000 particles of skin every hour. You may not think much about losing skin if yours isn’t dry or flaky or peeling from a sunburn, but your skin is constantly renewing itself and shedding dead cells.
  5. Every day an adult body produces 300 billion new cells. Your body not only needs energy to keep your organs up and running but also to constantly repair and build new cells to form the building blocks of your body itself.
  6. Every tongue print is unique. If you’re planning on committing a crime, don’t think you’ll get away with leaving a tongue print behind. Each tongue is different and yours could be unique enough to finger you as the culprit.
  7. Your body has enough iron in it to make a nail 3 inches long. Anyone who has ever tasted blood knows that it has a slightly metallic taste. This is due to the high levels of iron in the blood. If you were to take all of this iron out of the body, you’d have enough to make a small nail and very severe anemia.
  8. The most common blood type in the world is Type O. Blood banks find it valuable as it can be given to those with both type A and B blood. The rarest blood type, A-H or Bombay blood due to the location of its discovery, has been found in less than hundred people since it was discovered.
  9. Human lips have a reddish color because of the great concentration of tiny capillaries just below the skin.The blood in these capillaries is normally highly oxygenated and therefore quite red. This explains why the lips appear pale when a person is anemic or has lost a great deal of blood. It also explains why the lips turn blue in very cold weather. Cold causes the capillaries to constrict, and the blood loses oxygen and changes to a darker color.

A Few More Fascinating Facts:

Here are a few things you might not have known about all different parts of your anatomy.

  1. The colder the room you sleep in, the better the chances are that you’ll have a bad dream. It isn’t entirely clear to scientists why this is the case, but if you are opposed to having nightmares you might want to keep yourself a little toastier at night.
  2. Tears and mucus contain an enzyme (lysozyme) that breaks down the cell wall of many bacteria. This is to your advantage, as the mucus that lines your nose and throat, as well as the tears that wet your eyes are helping to prevent bacteria from infecting those areas and making you sick.
  3. Your body gives off enough heat in 30 minutes to bring half a gallon of water to a boil. If you’ve seen the Matrix you are aware of the energy potentially generated by the human body. Our bodies expend a large amount of calories keeping us at a steady 98.6 degrees, enough to boil water or even cook pasta.
  4. Your ears secrete more earwax when you are afraid than when you aren’t. The chemicals and hormones released when you are afraid could be having unseen effects on your body in the form of earwax. Studies have suggested that fear causes the ears to produce more of the sticky substance, though the reasons are not yet clear.
  5. It is not possible to tickle yourself. Even the most ticklish among us do not have the ability to tickle ourselves. The reason behind this is that your brain predicts the tickle from information it already has, like how your fingers are moving. Because it knows and can feel where the tickle is coming from, your brain doesn’t respond in the same way as it would if someone else was doing the tickling.
  6. The width of your arm span stretched out is the length of your whole body. While not exact down to the last millimeter, your arm span is a pretty good estimator of your height.
  7. Humans are the only animals to produce emotional tears. In the animal world, humans are the biggest crybabies, being the only animals who cry because they’ve had a bad day, lost a loved one, or just don’t feel good.
  8. Right-handed people live, on average, nine years longer than left-handed people do. This doesn’t have a genetic basis, but is largely due to the fact that a majority of the machines and tools we use on a daily basis are designed for those who are right handed, making them somewhat dangerous for lefties to use and resulting in thousands of accidents and deaths each year.
  9. Women burn fat more slowly than men, by a rate of about 50 calories a day. Most men have a much easier time burning fat than women. Women, because of their reproductive role, generally require a higher basic body fat proportion than men, and as a result their bodies don’t get rid of excess fat at the same rate as men.
  10. Koalas and primates are the only animals with unique fingerprints. Humans, apes and koalas are unique in the animal kingdom due to the tiny prints on the fingers of their hands. Studies on primates have suggested that even cloned individuals have unique fingerprints.
  11. The indentation in the middle of the area between the nose and the upper lip has a name. It is called the philtrum. Scientists have yet to figure out what purpose this indentation serves, though the ancient Greeks thought it to be one of the most erogenous places on the body.


Yatheendradas C.k. at 09:15 PM - Mar 11, 2015 ( )

Image Collection:

Human Anatomy

Illustration of the human colon

Picture of the Colon


The colon is also called the large intestine. The ileum (last part of the small intestine) connects to the cecum (first part of the colon) in the lower right abdomen. The rest of the colon is divided into four parts:

• The ascending colon travels up the right side of the abdomen.
• The transverse colon runs across the abdomen.
• The descending colon travels down the left abdomen.
• The sigmoid colon is a short curving of the colon, just before the rectum.

The colon removes water, salt, and some nutrients forming stool. Muscles line the colon's walls, squeezing its contents along. Billions of bacteria coat the colon and its contents, living in a healthy balance with the body.


Yatheendradas C.k. at 10:57 AM - Mar 15, 2014 ( )

Reproductive System

Know Your Body - Amazing Facts About the Reproductive System

Female Reproductive System

• The vulva is the external part of the female reproductive system. The vulva covers the opening to the vagina and other parts of the reproductive system inside the body. The fleshy area just above the top of vaginal opening is called the mons pubis. 

• The clitoris is a small sensory organ located towards the front of the vulva. The clitoris is covered by a fold of skin called the prepuce, which is similar to the foreskin at the end of the penis. Like the penis, the clitoris is sensitive to stimulation and can become erect.

• The vagina is a muscular canal that connects the lower parts of the uterus or womb at the cervix, to the outside part of the body, also known as birth canal. 

• The structure that covers the opening of the vagina is a thin sheet of tissue with one or more holes in it called the hymen. Hymen are often different from one female to another.

• The uterus is the most important organ in the female reproductive system. It is a small organ, measuring about 3 inches (7.5 centimeters) long and 2 inches (5 cm) wide. During pregnancy the uterus greatly increases in size as the baby develops up to 20 times the normal size. 

• The ovaries are the first reproductive system organs to develop in a female body. They are located on either side of the uterus. The ovaries are small, oval-shaped glands that store, produce and release eggs into the fallopian tubes in the process called ovulation. The ovum or the egg present in the ovaries is the largest cell in the female human body. The ovaries are also part of the endocrine where the women produce eggs and hormones such as estrogens and progesterone

• Fallopian tubes are narrow tubes about 12 centimeters long that are attached to the upper part of the uterus. It serves as a tunnel for the eggs that are produced in the ovaries during the female reproductive system.

• In the womb, the baby's body is covered by a thin layer of hair but as soon as the baby is born it disappears.The female human body is capable of giving birth to 35 children in one lifetime.

Male Reproductive System

• The penis is the external structure in the male reproductive system. It is a tubular muscular organ, and it is made up of three parts: the root, which attaches to the wall of abdomen, the shaft and the glands, a cone-shape at the tip of the penis. 

• The scrotum is a loose pouch-sac like of skin that hangs behind and below the penis. It contains the testicles (also called testes), as well as many nerves and blood vessels. The scrotum acts as a protective layer around the testes. 

Male Reproductive System

• The testicles (testes) are oval organs that lie in the scrotum. The organ is about the size of large olive. Within the testes are coiled masses of tubes called seminiferous tubules. These testes are responsible for producing sperm cells. The testes are also responsible for making the testosterone, the primary male sex hormone and for generating sperm.

• The epididymis is a long, coiled tube that rests on the backside of each testicle. Its function is to carry and store sperm cells that are produced in the testes. The epididymis also brings the sperm to maturity, since the sperm that emerge from the testes are immature and incapable of fertilization. 

• The vas deferens is a long muscular tube that connects from the epididymis into the pelvic cavity, to just behind the bladder. The vas deferens transports mature sperm to the urethra in preparation for ejaculation.

• The urethra is a tube that carries urine or sperm to outside of the body. In males, its function is ejaculation of semen when the man reaches orgasm. During sex when the penis is erect, the flow of urine is blocked from the urethra and allows only semen to be ejaculated at orgasm.

• Other internal structures that are responsible for providing fluids that lubricate the duct in the system and nourish the sperm cells are the prostate glands, seminal vesicles and bulbourethral gland or Cowper’s gland. 

• About 500 million sperm mature every day in a normal male adult. The average life span of a sperm is about 36 hours.

Male Reproductive System Female Reproductive System

Reproduction is one of the most important and fundamental properties of living organisms by which every kind of living organism multiplies to form new individuals of it’s own kind. In this process, one generation of living organisms gives rise to the next generation. This process is not essential to the life of any individual but is a function essential for the life of the species.

The continuity of life has been possible from the time of its origin, millions of years ago upto the present day, only due to the phenomenon of reproduction-in fact, perpetuation of self and of the species is one of the most remarkable features of living organisms. A species is a group of related animals, plants or microbes that can interbreed to produce a fertile offspring. The preservation of species has been made possible because the parents produce offspring like themselves. It is also the means of increasing the population of a species. It plays a major in evolution by transmitting advantageous changes / variations from organisms of one generation to those of the next.

In human beings, the process is one of sexual reproduction, which involves both male and female sexes. The new individual or offspring develops from the fusion cell called zygote, which is formed, by the fusion or union of two specialized cells called germ cells, sex cells or gametes.

Generally, one of the gametes is active, smaller in size and without any reserve food. This is the male gamete and it is called the sperm.

The male reproductive system of a man consists of a pair of testes, ducts, accessory glands and a penis. The functions of the male reproductive system are:
1. Production of sperms.
2. Transmission of sperms to the female.

The female reproductive system consists of two ovaries (produce ova and female hormones), Fallopian tubes, uterus (muscular organ which supports the fetus during it’s 40 week gestation period before birth), vagina and external genitalia.

The functions of the female reproductive system are: -
1. Production of ovum eggs.
2. Receiving the sperms.
3. Providing suitable environment for fusion (fertilization) of the egg and the sperm.
4. Child birth.
5. Nourishment of the baby with breast milk until it can take a mixed diet.


Yatheendradas C.k. at 07:45 PM - Mar 14, 2014 ( )

Digestive System

Know Your Body - Digestive System

1. For every 2 weeks, the human stomach produces a new layer of mucous lining, otherwise the stomach will digest itself.

2. The human liver performs 500 different functions.

3. Liver is the largest and heaviest internal organ of the body and weighs about 1.6 kilos.

4. The Liver is the only organ of the body, which has the capacity to regenerate itself completely even after being removed almost completely.

5. Liver cells take several years to replace themselves.

6. A healthy liver processes 720 liters of blood per day.

7. The human stomach contains about 35 million small digestive glands.

8. The human stomach produces about 2.5 liters of gastric juice  everyday.

9. In an average person, it takes 8 seconds for food to travel down the food pipe, 3-5 hours in small intestine and 3-4 days in the large intestine.

10.  The human body takes 6 hours to digest a high fat meal and takes 2 hours for a carbohydrate meal.

Living organisms need food 

a) In order to keep alive and to carry on their various life activities such as ingestion, digestion, absorption, respiration, movement, circulation, co-ordination, secretion, excretion and reproduction 

b) For building and maintaining their cellular and metabolic machinery (growth maintenance and repair of the organism) 

c) For regulating metabolic processes. 

d) For building up the resistance against disease 

Food thus can be defined as any essential substance that when absorbed into the body tissues yields materials for the production of energy, the growth and regulation of life processes, without harming the organism. 

1. The particles or pieces of food, small or big are taken into the body. This is called as eating or ingestion. 

2. The ingested food is then digested, where the complex and large food particles are broken down into simpler, smaller and soluble molecules. 

3. Then, the simpler substances obtained from digestion are then absorbed into the cells of the body. 

4. Then the undigested waste material is removed and thrown out of the body by excretion. The process of digestion includes mechanical and chemical breakdown of the ingested food. 

The chunks of food chewed by us are broken down into small pieces and are acted upon a variety of enzymes secreted into the mouth. Thus, inside the mouth, saliva moistens the masticated food and causes chemical digestion (of starch by the amylase enzymes into smaller molecules). The masticated food and partially digested food then passes the esophagus or the food pipe into the stomach. Here, it is acted upon by gastric juice of the stomach, which contains hydrochloric acid, pepsin and other enzymes. These enzymes break down the proteins of the food into smaller molecules, which pass onto small intestine. 


In the first part of the small intestine, called the duodenum, food (now called chyme) is acted upon the by bile juice from the liver and pancreatic juice from the pancreas. The walls of a part of small intestine called ileum also pour some enzymes for food digestion. 

Digestive System

All the food, which is digested by the mouth, stomach, duodenum and ileum, is ultimately absorbed by the villi, which are numerous minute finger like projections into the cavity of the small intestine. The absorbed food is then sent through blood to different parts of the body. The absorbed food materials are utilized by the body in various ways, by a process called assimilation. The undigested food is sent to the large intestine and removed through the rectum and anus in the form of stool or faeces. This process is called excretion.


Yatheendradas C.k. at 06:37 PM - Mar 13, 2014 ( )

Endocrine Syste

know your Endocrine system
Similar to plants, certain special chemicals called hormones regulate the various activities of our body. Hormones are chemical messengers, which help in controlling and coordinating the activities of the body. They are produced by endocrine glands. The hormone in other words acts as a switch or a trigger for a certain action to take place.
The endocrine glands are under the control of the nervous system.

The endocrine system of human beings consists of the following glands:

1. Hypothalamus And Pituitary Gland
2. The Pineal Gland
3. The Thyroid Gland
4. The Parathyroid Glands
5. The Adrenal Glands
6. Islets Of Langerhans (Pancreas)
7. Ovaries (Female)
8. Testes (Male)

1 Pituitary (Master Gland) Base of fore brain, pea shaped Growth Hormone Regulates the growth of bone and tissue.
      Anti-diuretic hormone Controls amount of water reabsorbed by the kidney
      Adreno corticotrophic hormone Defending the body against physiological stress eg. exposure to cold Follicle stimulating hormone Stimulates ovary to produce female hormone
      Thyroid stimulating hormone Stimulates thyroid to produce its hormone
2 Thyroid Neck of lower extremity of larynx, butterfly shaped Thyroxine Regulates rate of growth and metabolism. Too little over weight and sluggishness. Too much- thinning and over activity.
3 Adrenal A Pair of cap shaped organs above each kidney Cortisone Aids in conversion of proteins to sugar, cortex of this gland produces the hormone.
4 Pancreas It’s a double gland Insulin Regulates Sugar metabolism. Too little insulin leads to high sugar level in blood and weakness (a condition called diabetes).
5 Ovary Lie on the lateral walls of the pelvis Estrogen Development of Secondary sexual characters. Eg. Development of breasts in female.
6 Testis In the scrotum Testosterone Development of many masculine features such as growth of moustaches and beard.


Yatheendradas C.k. at 06:33 PM - Mar 13, 2014 ( )

Endocrine system

Know Your Body - Endocrine system


1. The human body contains 30 amazing hormones, which regulates activities like sleep, body temperature, hunger, and managing stress in times of crisis and so on.

Similar to plants, certain special chemicals called hormones regulate the various activities of our body. Hormones are chemical messengers, which help in controlling and coordinating the activities of the body. They are produced by endocrine glands. The hormone in other words acts as a switch or a trigger for a certain action to take place.

The endocrine glands are under the control of the nervous system.

The endocrine system of human beings consists of the following glands:

1. Hypothalamus And Pituitary Gland
2. The Pineal Gland
3. The Thyroid Gland
4. The Parathyroid Glands
5. The Adrenal Glands
6. Islets Of Langerhans (Pancreas)
7. Ovaries (Female)
8. Testes (Male)

Yatheendradas C.k. at 07:24 PM - Mar 12, 2014 ( )

Respiratory System

Know Your Body - Respiratory System

1. We breathe 13 pints of air every minute.

2. Each lung contains 300-350 million respiratory units called alveoli making it a total of 700 million in both lungs.

3. More than half a liter of water per day is lost through breathing.

4. People under 30 years of age take in double the amount of oxygen in comparison to a 80 year old.

5. Yawning brings more oxygen to the lungs

Human beings like other land animals breathe though their nostrils in noses and with the help of lungs. A pair of lungs are located in the airtight thoracic cavity that is bounded by a convex muscular and elastic sheet called diaphragm.

Functionally, the lungs are elastic bags resembling rubber balloons. They lack any muscle, which may allow them to expand or contract by themselves.

In normal breathing, through the nose, air travels through the nasal passages that are lined with ciliated mucous epithelium. Here, it is cleaned and warmed. Sensory cells detect odours. As air continues through the pharynx or throat, it crosses the path of food. This is why we can breathe through the mouth. Then, air passes the epiglottis, enters the larynx or voice box, and goes down the trachea or windpipe. A bronchus runs to each lung, divides in a tree like manner to give smaller bronchioles and finally deposits the air in the microscopic thin walled air sacs or alveoli (singular alveolus). A group of alveoli appears like a cluster of grapes and gives the lungs, a sponge like structure. There are about 150 million alveoli in each lung and altogether they cover a very large surface area (approximately 70 square metres).


The alveoli are lined by a layer of moist flat epithelial cells and surrounded by networks of blood capillaries. The blood, which flows to the lungs by pulmonary artery, contains little oxygen and much carbon dioxide. On the other hand, the air in the alveoli has a high concentration of oxygen and relatively less carbon dioxide. Thus a 2-way diffusion takes place through the cells of the capillaries. Oxygen enters the blood and CO2 leaves it. Since enormous breathing surface of lungs is exposed to the external environment the exchange of gases is computed within a few seconds.


Aravind Prabhu at 08:01 PM - Mar 11, 2014 ( )

Sir, a wonderful thread. We have more to be revealed. Reveal them also. Thanks.

Yatheendradas C.k. at 06:23 PM - Mar 11, 2014 ( )

Skin and Hair

Know Your Body - Skin  and Hair
1. 80 hairs are likely to fall every day.

2. The human skin contains 45 miles of nerves.

3. In one square inch of skin there are 4 yards of nerve fibers.

4. On An average the human scalp has 100,000 hairs. 

5. Fingernails grow faster than toenails.

6. Nails of toes and fingers take about 6 months to grow from base to tip.

7. In one square inch of skin, there are 3 million cells.

8. The total weight of skin in an average human adult is 61 pounds.

9. There are 100 receptors in each of our fingertips.

10.The human skin contains 280,000 heat receptors.

The skin, which forms the outer covering of the body, has a surface area of about 1.5 - 2m2 in adults and it contains glands, hair and nails.

Structure of Skin: 

Skin is made up of two layers: 
 The epidermis (or, outer covering) 
 The dermis (or, true skin) 

The epidermis: 

 The outermost part of the epidermis consists of flat, dead cells that are constantly being shed 

 The underlying part of the epidermis is made up of rapidly dividing cells. These are continually pushing upwards and replacing the dead cells above them. 

 Specialized epidermis cells that extend downwards into the dermis produce hair and nails, which are also composed of dead cells. 

The dermis: 

The dermis is made up of tiny blood vessels and nerve endings that are densely woven into the flexible connective tissue. Sweat glands and oil glands are embedded in it. 

General Features of Skin: 

 It is a barrier against germs, and a tough resilient cushion that protects the tissues underneath, and helps to regulate the body temperature. 

 When it is hot, glands in the skin secrete sweat, the evaporation of which causes cooling. Or when it is cold, constriction of the blood vessels in the skin cuts down the flow of blood near the body’s surface and so reduces heat loss. 

 Just below the surface of the skin are millions of tiny nerve endings. These are the touch receptors which tell us about the world through five different kinds of sensations pain, cold, heat, pressure and contact 

 The skin supplies much of the body’s vitamin D requirement by producing substances that changes into vitamin D when it is exposed to the Ultraviolet radiation in sunlight. 

 The thickness of the skin and the number of special structures vary in different parts of the body. 

 Skin is thinnest on the lips and thickest on the scalp, palms of the hands and soles of the feet (Continual pressure or friction can cause skin to thicken) 

 Hair follicles are found on nearly the whole body, being abundant on the scalp but absent in the skin of the soles and palms. 

 Sweat glands, oil glands and nerve endings are also unevenly distributed. There is a concentration of sweat glands in the armpits; nerve endings are most abundant in the lips and fingertips. 

 Skin owes its colour partly to the blood, redness of which shows through translucent tissues, and partly to various pigments in the epidermis


Yatheendradas C.k. at 07:46 PM - Mar 10, 2014 ( )

Urinary System

Know Your Body - Urinary System

1. The Human bladder can stretch to hold about 400ml of urine.

2. All the blood in our body passes 400 times through each kidney every day.

Excretion can be defined as the removal of toxic waste products of metabolism from the body. These wastes can be either solid, liquid or in the gaseous state. The liquid wastes are ammonia and urea, which exist in the blood along with the nutrients and other useful substances. So there is a need of complex organ that may separate or filter out the dissolved excretory wastes from blood while retaining the nutrients in the latter. Two kidneys in human beings are such organs that perform this task. There is a distinct advantage of the two kidneys in our body. If one kidney fails, the other can still deal with functions of excretion and regulation. 

urinary system

The kidneys are solid; bean shaped, reddish brown-paired structure, which lie in the abdominal cavity one on either side of the vertebral column. They are about 11 to 12 cms in length, 5 to 6 com in breadth and about 3 cms in thickness and weigh about 120 to 150 gms each. The kidney is approximately the size of your fist. They are well protected and lie in the retro-peritoneal section of the abdomen which means that they lie behind the stomach and other digestive organs and nearer to the back of the body. 

kidney internal structure

A cross section of the kidney shows a darker outer zone called the cortex and a lighter inner zone called the medulla. A funnel shaped hollow pelvis meets the ureter and the junction is called the pelvi-ureteric junction. This junction can have a functional blockage giving rise to obstruction to flow of the kidney. 

Each kidney is made up of about 1 million tubules that are the basic functioning unit of the kidney that can make urine and these are known as nephrons. About 180 litres of blood, which run through these nephrons daily produces just one to two liters of urine by the process of filtration, reabsorbtion and secretion by the nephrons. The urine enters the pelvis of the kidney where it collects and continues down the ureters to the bladder. In the urinary bladder urine is temporarily stored and is finally eliminated from the body. The bladder has an average capacity of about 400 milliliters. The urinary bladder is a muscular reservoir for the urine and can expand without exerting any pressure within the bladder. It function is to store and evacuate urine. The urine is released periodically to the outside via the urethra.



Yatheendradas C.k. at 11:33 AM - Mar 09, 2014 ( )

Circulatory System

know Your Body - Circulatory System
1. The heart muscles will stop working only when we die.

2. Every second, 15 million blood cells are destroyed in the human body.

3. Platelets, which form a part of the blood cell component are produced at  the rate of 200 billion per day.

4. An adult human body contains five to six liters of blood and an infant  has about one liter of blood.

5. Except the heart and lungs, all the other parts of the body receive their blood supply from the largest artery of the body, the aorta.

6. The Pulmonary vein is the only vein in the human body that carries oxygenated blood while all the other veins of the body carries de-oxygenated blood.

7. Human blood is colorless. It is the hemoglobin; a pigment present in the red blood cells that is responsible for the red color of the blood.

8. Heartbeat is nothing but the sound produced by the closure of valves of the heart when the blood is pushed through its chamber.

9. A women's heart beat is faster than that of a man's.

10.The human heart continues to beat even after it is taken out  of the body or cut in to pieces.

Human circulatory system consists of blood which is kept in motion or circulation by the pump called the heart and the pipes called blood vessels. The heart is a non stop pump that pushes the blood through the arteries and supplies the body cells oxygen and glucose along with other essential nutrients. The waste from the cells including carbon di-oxide is brought back through the veins and pumped by the heart into the lungs for purification.

In human beings and other multicellular animals the transport of oxygen and nutrients for the cells of the body takes place by a fluid medium called the blood. The blood constantly moves around the body by the circulatory system. 

Blood is an important fluid connective tissue and composed of the following components. 


· Plasma 
· Formed Elements (R.B.C, W.B.C, PLATELETS) 

Formed Elements: 

1. R.B.C (Red Blood Cells or Erythrocytes) 

· Total Number = 5 million cells/ cubic mm of blood 
· Shape = dumbbell shaped 
· Nuclei = absent 
· Main Constituent= hemoglobin (a red pigment which is made up of protein and iron) 

2. W.B.C. (White Blood Cells or Leucocytes) 
· Total Number = 7000-10,000 cells / cubic mm of blood 
· Nuclei = present 
· Function = WBC consume bacteria, viruses and debris that enter the body and form special proteins, called antibiotics that protect against infection. 

3. PLATELETS:- (or Thrombocytes) 
· Total Number = 400,000 / cubic mm of blood. 
· Function = important role in the formation of a solid plug called clot at the site of injury to a blood vessel, so as to prevent further loss of blood. 

 It is the liquid part of blood into which float different types of blood cells; i.e. RBC, WBC & platelets; 
- It contains several salts, glucose, amino acids, proteins, hormones, and also digested and excretory products of food. 
- Serum is blood plasma from which the blood clotting protein called fibrinogen is removed. 

How The Circulatory System Functions: 

The heart is the muscular pump like organ that circulates blood through the body. The muscles of the heart contract periodically and cause the heart to pump blood. The heart contracts about 72 times a minute when an adult person is at rest, but this rate increases to 100 or more during activity or excitement. The total volume of blood in the system is about 5 to 6 litres. The heart pumps approximately 5 litres of blood out every minute. 


Blood Vessels: 
The 3 types of blood vessels are arteries, veins and capillaries and they are all connected to form one continuous closed system. 

Blood Vessels

They are the widest blood vessels having thick and elastic walls; arteries branch out into thinner tubes called arterioles, which again branch into thinner capillaries. 

Capillaries are tiny blood vessels with walls that are just one cell thick. These walls are permeable to water and CO2, which are exchanged with tissues surrounding the capillaries. Capillaries ultimately joint to form venules and at last veins return blood to the heart. 

Thus, arteries take blood from the heart and supply it to various tissues via the capillaries and veins return blood from the tissue to the heart. For maintaining such a unidirectional flow of blood, large veins have valves in them. The pressure of blood flow opens them in the directional of flow and closes them otherwise. 

Arterial blood is rich in oxygen and dissolved food, while venous blood carries CO2 and waste material. However, pulmonary artery and pulmonary vein form two important exceptions to it. Pulmonary artery supplies lungs CO2 - rich blood and pulmonary vein collects oxygen - rich blood from lungs and sends it to heart.


Raaghavan Karthikeyan at 11:29 AM - Mar 08, 2014 ( )


Yatheendradas C.k. at 09:12 AM - Mar 08, 2014 ( )

Interesting Facts about nervous system

1. A newborn baby's brain grows almost 3 times during the course of its first year.

2. The left side of human brain controls the right side of the body and the right side of the brain controls the left side of the body.

3. A New born baby loses about half of their nerve cells before they are born.

4. As we get older, the brain loses almost one gram per year.

5. There are about 13, 500,00 neurons in the human spinal cord.

6. The total surface area of the human brain is about 25, 000 square cm.

7. The base of the spinal cord has a cluster of nerves, which are most sensitive. 

8. An average adult male brain weighs about 1375 grams.

9. An average adult female brain is about 1275 grams.

10. Only four percent of the brain's cells work while the remaining cells are kept in reserve.

Yatheendradas C.k. at 09:09 AM - Mar 08, 2014 ( )

Nervous system

1. A newborn baby's brain grows almost 3 times during the course of its first year.

2. The left side of human brain controls the right side of the body and the right side of the brain controls the left side of the body.

3. A New born baby loses about half of their nerve cells before they are born.

4. As we get older, the brain loses almost one gram per year.

5. There are about 13, 500,00 neurons in the human spinal cord.

6. The total surface area of the human brain is about 25, 000 square cm.

7. The base of the spinal cord has a cluster of nerves, which are most sensitive. 

8. An average adult male brain weighs about 1375 grams.

9. An average adult female brain is about 1275 grams.

10. Only four percent of the brain's cells work while the remaining cells are kept in reserve.

The Central nervous system consists of the brain, the spinal cord, and the body’s nerve network. This complex system is based on one kind of cell the neurons. The brain, the mass of tissue inside the head, has the greatest number of these cells, most of which are in it’s outer part, the cerebrum. Below the cerebrum is the cerebellum and the brain stem, which is linked to the spinal cord.

The Brain: The brain has been compared to a giant telephone exchange or to a computer. It functions as both, handling incoming and out going calls, and making decisions, as diverse as whether to laugh or cry and whether the temperature of the body should be higher or lower, on the basis of information fed into it.


Cerebrum: The brain’s most obvious external features are two soft hemispheres, which make up the cerebrum. These hemispheres make up 70% of the whole brain and nervous system. They are “mirror images” of each other, and each is chiefly concerned with the movements and sensations of only one side of the body. Sensations on the right side of the body and the control of the muscles on that side are functions of the left hemisphere, and vice versa. It consists of 2 layers: (1) outer cortex or grey matter - which is the decision maker of the brain, (2) Inner layer of white matter - made up of nerve fibers.

Cerebellum: The cerebellum functions below the level of consciousness. It is concerned with balance, and is the center for the co-ordination of complex muscular movements

Brain Stem: Links the spinal cord to the brain. They lie below the cerebral hemispheres.

The Spinal Cord: The spinal cord is the body’s main nerve trunk-a cylinder of nerve tissue 18 inches long about as thick as a man’s little finger. It runs down the back from the medulla oblongata, at the base of the brain. It is enclosed in a set of 3 membranes, similar to those surrounding the brain. Between the layers of membranes, Cerebro-spinal fluid acts as a cushion, to protect the cord from damage.

Nerve Fibres: The spinal cord is a column of nervous tissue, which is spread throughout the body; they carry impulses to and from the brain. Nerve fibres from the brain and spinal cord are bundled together to form 12 pairs of cranial nerves, connected to the brain and 31 pairs of spinal nerves

Spinal Nerves:
1) CERVICAL NERVES - (8 pairs) serve mainly the arms.

2) THORACIC NERVES - (12 pairs) lead to the sternum, internal organs and muscles of the chest.

3) LUMBAR NERVES - (5 pairs) serve the abdominal wall and legs.

4) SACRAL & COCCYGEAL NERVES - (6 pairs) lead mainly to the legs.

Carnival Nerves:
The brain has links with the sense organs and the muscles of the head by means of 12 pairs of cranial nerves

1) OLFACTORY: - sense of smell

2) OPTIC: - sense of sight balance

3) OCULOMOTOR: - Focusing, regulating the size of the pupil, balance

4) TROCHLEAR: - movement of the eyeball.

5) TRIGEMINAL: - Chewing, sensation from the face

6) ABDUCENT: - movement of eye, sense of taste

7) FACIAL: - movements of facial expression

8) VESTIBULOCOCHLEAR: - maintenance of balance, sense of hearing

9) GLOSSOPHARYNGEAL: - secretion of saliva, sense of taste, movement of pharynx

10) VAGUS: - movement and secretion

11) ACCESSORY: - movement of the head, shoulders, pharynx and larynx

12) HYPOGLOSSAL: - movement of tongue.

Autonomic Nervous System: The autonomic system controls glands, such as the salivary glands, and the internal organs-the bladder, heart, intestines, liver, lungs and sexual organs. Nearly all the actions of the autonomic system are outside voluntary control eg. You cannot normally “will” your heart to beat faster; but if you are given a fight, your pulse involuntarily speeds up.
The autonomic division of the nervous system consists of two opposing parts,

>>The sympathetic;
>>The parasympathetic; which operate below the level of consciousness
>>The sympathetic nerves: - Through the sympathetic nerves, the brain mobilizes the body for action to meet possible danger.

1) IRIS- Changes size, when someone is frightened or angry, the brain stimulates the sympathetic nerves to their part of the eye, causing the pupils to open wide.

2) SALIVARY GLANDS- produces less saliva, so that the mouth goes dry.

3) LUNGS & WINDPIPE- are affected under stress; breathing becomes faster, so that the body gets more oxygen.

4) HEART- pumps faster, during times of fear & anger. Normally you are unaware of the beating of the heart, but its increased activity in times of excitement raises the blood pressure, pumping more blood to supply energy for muscles.

5) ADRENAL GLANDS- at the top of the kidneys secrete the hormone adrenaline, which prepares the body to fight or run away

6) LIVER-releases glucose under emotional stress, providing extra energy for muscles.

7) STOMACH & INTESTINES- have their blood diverted to the heart, CNS and muscles, so that they can operate under stress. The wave like movements of the intestinal walls stop, and the various sphincters close. ·

Parasympathetic Nerves: - are concerned with restoring the body to peaceful activity after an emergency

1) Heart - slows down & the blood pressure falls after the danger is over.

2) Bladder - can be contracted and it’s sphincter may open, causing urination.

Hemant Parikh at 04:29 PM - Mar 07, 2014 ( )


Yatheendradas C.k. at 04:12 PM - Mar 07, 2014 ( )

MusculoSkeletal system

1. At birth we have over 300 bones. As we grow up, some of these bones fuse together as a result an adult has only 206 bones.

2. The Human hand has 27 bones.

3. The Femur, or thigh bone is the longest bone in our body and is about a quarter of our height.

4. The human body has 230 movable and semi- movable joints.
5. The Human skull is made up of 29 different bones
6. The strongest muscles of the human body are masseters, these are present on either side of the mouth and help with chewing and grinding food in our mouth.
7. The Thighbone is so strong that it withstands the axial load of about 1600-1800 kilos.
8. Most of the bones in the human body constitutes about ¾ of water.
9. The whole leg consists of 31 bones.
10.Almost every seven years, the human body replaces the equivalent of an entirely new skeleton.

Bones: More than 206 bones support the body and provide protection for organs such as the brain, heart and lungs. The bones of the skeleton act as a frame to which muscles are attached. These skeletal muscles allow the body to move; they are attached to bones by bands of tough elastic tissue, called tendons, and it is by means of tendons that they exert their pull. Another important task of bones is to produce blood cells. Finally, the bones provide a store of chemicals such as calcium salts, which are released into the bloodstream, as they are needed.

Types of bones: -
Man has evolved with bones specialized into four main types, each with a different role:-
1) The long bones: - eg:- in the limbs, they are thin, hollow and light, they play as essential role in all types of movements.
2) Flat Circular bones: - eg:- bones that form the spine or vertebral column
3) Long Circular Bones: - eg. Ribs, they are strong but elastic giving the chest the flexibility and springiness it needs for breathing.
4) Flat irregular bones: - eg:- shoulder, blades, hips and skull these are strong but light and protect delicate organs, such as the brain.

The framework of the body: -
The body owes its shape & support to the skeleton a frame consisting of hundreds of jointed bones.

Head : The bones of the skull surround & protect the brain; the lower jaw is hinged to the skull.


Chest : The bony cage of the ribs, connected to the spine at the back and the breastbone at the front, surround and protect the organs in the chest.


Arm : The bones of the arms are jointed to sockets in the shoulder blades.

Spinal Column : The 7 vertebrae in the neck and the 20 in the back make the spinal column.

Spinal Column

Pelvis : The bones of the pelvis surround the lower abdominal organs, support the spine and provide attachment for the legs.


Hand : Eight bones make up the wrist, five the palm, and 14 hinged bones form the fingers and thumb.


Leg : Three major leg bones are suspended by ball and socket joints from the pelvis

Leg bone

Foot : The bones of the foot form arches, so that the weight is carried on the heel and toes.

foot bones

There are about 650 muscles in the body, and they are divided into three different types, skeletal, visceral and cardiac The skeletal muscles move the arms, legs, and spine The visceral muscles control movements in the walls of blood vessels, the stomach and intestines. The cardiac muscles produce the pumping action of the heart. All the muscles are present in the body at birth, and everyone has the same number of muscles, consisting of the same number of fibres.


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