52 Interesting 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 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 superspeedy 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 deep 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 23 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 60100 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 it’s flammability, human hair decays at such a slow rate that it is practically nondisintegrative. 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 razorblades. While you certainly shouldn’t test the fortitude of your stomach by eating a razorblade 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 mucuslike 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, grapelike 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 soft ball. 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 waterfilled, 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 gases 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 oxen 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 unique human traits: fingerprints. At only 613 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.