People will often say they know something "like the back of their hand" to indicate that they're familiar with it top to bottom. But how much do you actually know about your own body? We've got 16 tidbits that may surprise you.
1: Tongue Print
Don't stick out your tongue if you want to hide your identity. Similar to fingerprints, everyone also has a unique tongue print!
2: Shedding
Your pet isn't the only one in the house with a shedding problem. Humans shed about 600,000 particles of skin every hour. That works out to about 1.5 pounds each year, so the average person will lose around 105 pounds of skin by age 70.
3: Bone Count
An adult has fewer bones than a baby. We start off life with 350 bones, but because bones fuse together during growth, we end up with only 206 as adults.
4: New Stomach
Did you know that you get a new stomach lining every three to four days? If you didn't, the strong acids your stomach uses to digest food would also digest your stomach.
5: Scent Remembering
Your nose is not as sensitive as a dog's, but it can remember 50,000 different scents.
6: Long Intestines
The small intestine is about four times as long as the average adult is tall. If it weren't looped back and forth upon itself, its length of 18 to 23 feet wouldn't fit into the abdominal cavity, making things rather messy.
7: Bacteria
This will really make your skin crawl: Every square inch of skin on the human body has about 32 million bacteria on it, but fortunately, the vast majority of them are harmless.
8: Source of Body Odor
The source of smelly feet, like smelly armpits, is sweat. And people sweat buckets from their feet. A pair of feet have 500,000 sweat glands and can produce more than a pint of sweat a day.
9: Sneeze Speed
The air from a human sneeze can travel at speeds of 100 miles per hour or more -- another good reason to cover your nose and mouth when you sneeze -- or duck when you hear one coming your way.
10: Blood Distance
Blood has a long road to travel: Laid end to end, there are about 60,000 miles of blood vessels in the human body. And the hard-working heart pumps about 2,000 gallons of blood through those vessels every day.
11: Saliva Quantity
You may not want to swim in your spit, but if you saved it all up, you could. In a lifetime, the average person produces about 25,000 quarts of saliva -- enough to fill two swimming pools!
12: Snore Loudness
By 60 years of age, 60-percent of men and 40-percent of women will snore. But the sound of a snore can seem deafening. While snores average around 60 decibels, the noise level of normal speech, they can reach more than 80 decibels. Eighty decibels is as loud as the sound of a pneumatic drill breaking up concrete. Noise levels over 85 decibels are considered hazardous to the human ear.
13: Hair Color and Count
Blondes may or may not have more fun, but they definitely have more hair. Hair color helps determine how dense the hair on your head is, and blondes (only natural ones, of course), top the list. The average human head 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. People with black hair tend to have about 110,000 follicles, while those with brown hair are right on target with 100,000 follicles. Redheads have the least dense hair, averaging about 86,000 follicles.
14: Nail Growth
If you're clipping your fingernails more often than your toenails, that's only natural. The nails that get the most exposure and are used most frequently grow the fastest. Fingernails grow fastest on the hand that you write with and on the longest fingers. On average, nails grow about one-tenth of an inch each month.
15: Head Weight
No wonder babies have such a hard time holding up their heads: The human head is one-quarter of our total length at birth but only one-eighth of our total length by the time we reach adulthood.
16: Need for Sleep
