Human Body Facts
The human heart pumps enough blood in a lifetime to fill three supertankers.
Every year about 98% of the atoms in your body are replaced.
If your eyes are blue, you share common ancestry with every other blue–eyed individual in the world.
An eagle's eyesight is eight times more powerful than a human. The human eye has some 200,000 vision cells and the eagles have 1.5 million.
As people age, their ears get larger. Ear circumference increases on average 0.51 millimeters per year.
The "absolute threshold" in humans for vision is a candle flame, 30 miles away, on a dark, clear night.
At least 30 million neurons in the entire visual cortex are activated by the single image of a house or face.
The "absolute threshold" in humans for touch is the wing of a bee falling from 1 centimeter onto your cheek.
The number of neurons in the neocortex of females is 19.3 billion; in males, the number of neurons in the neocortex is 22.8 billion.
Human hair is virtually indestructible.
We are about 1 cm taller in the morning than in the evening.
The human body is estimated to have 60,000 miles of blood vessels.
There are as many hairs per square inch on your body as a chimpanzee.
The acid in your stomach is strong enough to dissolve razorblades.
You could remove a large part of your internal organs and still 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.
You use 200 muscles to take one step.
A full bladder is roughly the size of a soft ball. 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.
It takes 17 muscles to smile and 43 to frown.
Bone is stronger than some steel.
Babies are always born with blue eyes.
Your body has enough iron in it to make a nail 3 inches long.
Your body gives off enough heat in 30 minutes to bring half a gallon of water to a boil.
Your brain is 80 % water.
Most people dream about 1-2 hours a night and have an average of 4-7 dreams each night.
The psychology of the brain shows that women tend to take longer to make a decision, but are more likely to stick with the decision, compared to men, who are more likely to change their mind after making a decision.
There are more nerve cells in the human brain than there are stars in the Milky Way.
Your retinas receive your vision of the outside world as upside–down.
Ommatophobia is fear of the eyes.
Your eyes can get sunburned. That's why it's important to wear sunglasses that protect you from UVA and UVB rays.
On average, the human eye can detect more than 10 million colors, but only distinguish about 30 shades of gray.
Newborn babies do not produce tears.
We blink on an average of 17 times per minute, 14,280 times per day, and 5.2 million times a year.
The eye muscle is the fastest reacting muscle in the body. It contracts in less than 1/100th of a second.
The heaviest human brain ever recorded weighed 5 lb., 1.1 oz (2.3 kg).
Humans can detect one molecule of green pepper smell when it is mixed in the air with 3 trillion other molecules.
The "absolute threshold" in humans for hearing: A ticking watch 20 feet away in a quiet place.
The skin of an adult human covers about 18-20 square feet (~2 square meters) and weighs about 6 lb (2.7 kg).
The "absolute threshold" in humans for smell is a drop of perfume in a three-room apartment.
If left alone, 70% of birthmarks gradually fade away.
One human hair can support 3 ounces.
The human eye blinks an average of 4,200,000 times a year.
One human hair can support 3.5 ounces.
Your eyes are always the same size from birth but your nose and ears never stop growing.
The lifespan of a human hair is 3 to 7 years on average.
If saliva cannot dissolve something, you cannot taste it.
A human head remains conscious for about 15 to 20 seconds after it is been decapitated.
The strongest muscle in the human body is the tongue.
Three hundred million cells die in the human body every minute.
The three things pregnant women dream most of during their first trimester are frogs, worms and potted plants.
Babies are, pound for pound, stronger than an ox.
Human lips have a reddish color because of the great concentration of tiny capillaries just below the skin.
Humans shed about 600,000 particles of skin every hour.
Nails and hair do not continue to grow after we die.
You get a new stomach lining every three to four days.
Fingernails grow nearly 4 times faster than toenails.
The hardest bone in the human body is the jawbone.
The indentation in the middle of the area between the nose and the upper lip 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.
The human brain is the fattest organ in the body.
Each square inch of human skin consists of 20ft of blood vessels.
Death will occur about 10 days without sleep, while starvation takes a few weeks.
71% of American chocolate eaters prefer milk chocolate.
The cerebral cortex makes up about 77% of the total volume of the human brain.
Information travels in the nerves at speeds up to 268 miles per hour (429 kilometers/hour).
The pupil of the eye can vary in diameter from 1.5 to 8.0 mm. Therefore, the amount of light entering the eye can change 30-fold.
People can distinguish between 3,000 and 10,000 different smells.
The average human brain weighs about 3 pounds (1.4 kilograms).
The human eye weighs about 7.5 g.
There are approximately 100 billion neurons in the human brain.
The weight of the human brain triples during the first year of life, going from 300 grams to 900 grams.
The average duration of a single blink is 0.1 - 0.4 seconds.
There are 1 quadrillion synapses in the human brain. That's 1,000,000,000,000,000 synapses! This is equal to about a half-billion synapses per cubic millimeter.
An average yawn lasts about 6 seconds.
Humans sleep for 17-18 hours a day at birth, 10-12 hours at age 4 and 7-8.5 hours by age 20.
Without myelin, the human brain would have to be 10 times bigger than it is now and we would have to eat 10 times as much to maintain our brain.
Taste buds are not just found on the tongue; they are also found on the palate, pharynx and larynx.
Facial hair grows faster than any other hair on the body.
The largest internal organ is the small intestine.
About 32 million bacteria call every inch of your skin home.
Everyone has a unique smell, except for identical twins.
Tears and mucus contain an enzyme (lysozyme) that breaks down the cell wall of many bacteria.
One out of every 2,000 newborn infants has a tooth when they are born.
Your ears secrete more earwax when you are afraid than when you arent.
The fastest growing nail is on the middle finger.
A baby's head is one-quarter of its total length, but by age 25 will only be one-eighth of its total length.
Information travels at different speeds within different types of neurons.
Humans can make do longer without food than sleep.
Women burn fat more slowly than men, by a rate of about 50 calories a day.
Your nose can remember 50,000 different scents.
Even small noises cause the pupils of the eyes to dilate.
The width of your arm span stretched out is approximately the length of your whole body.
Every tongue print is unique.
The feet account for one quarter of all the human body's bones.
The brain is much more active at night than during the day.
The adult human spinal cord weighs about 35 grams (0.1 lb).
In 1891, Wilhelm von Waldeyer coined the term "neuron."
The vagus nerve, important for controlling the functions of many internal organs, gets its name from the Latin word meaning "wandering."
The word "cerebellum" comes from the Latin words meaning "little brain."
Agenesis of the corpus callosum (ACC) is a birth defect in which the structure that connects the two hemispheres of the brain (the corpus callosum) is partially or completely absent.
The dura mater is the outermost covering of the brain. The term "dura mater" comes from Latin meaning "hard mother".
Each of your eyeballs is moved by six muscles.
The stapedius muscle is the smallest muscle in the body. This muscle, 6.3 mm in length, helps move the stapes bone in the middle ear.
The "absolute threshold" in humans for taste is a teaspoon of sugar in 2 gallons of water.
About 50 ml of blood travels through 100 g of brain tissue each minute.
Women metabolize caffeine about 25% faster than men.
The human cerebral cortex has an area of about 2.5 square feet, has 25 billion neurons, is interconnected by over 100,000 kilometers of axons and receives 300 trillion synapses.
The cerebellum makes up 10% of the total volume of the human brain.
Some of the oldest cells in the human body are neurons...they last a lifetime.
There are about 1,200,000 nerve fibers in each human optic nerve.
The eardrum (tympanic membrane) is only 0.1 millimeter thick and weighs only 14 milligrams.
Cerebrospinal fluid is 99% water.
The human cerebellum weighs about 150 grams.
The human retina contains approximately 120 million rods and 6 million cones. Rods are cells used in dim light; cones are cells used for color vision.
The length of myelinated nerve fibers in the brain is 150,000-180,000 km.
There are approximately 1 billion neurons in the human spinal cord.
There are 186 million MORE neurons in the left cerebral hemisphere of the brain than in the right hemisphere.
The aorta is nearly the diameter of a garden hose.
Your left lung is smaller than your right lung to make room for your heart.
Women's hair is about half the diameter of men's hair.
Every day an adult body produces 300 billion new cells.