1.The body's stomach acid is strong enough to dissolve zinc flakes, but the stomach wall has a protective layer to prevent itself from corroding.
2.The human brain can generate enough electricity to light a 10-watt light bulb.
3.A person's nose and ears are constantly growing throughout their lives.
4.The human eye sees less color at night than during the day, which is why the colors seen at night are duller than during the day.
5.The human body renews about 40,000 cells every minute.
6.The human heart beats about 100,000 times a day and will beat 2 billion to 3 billion times in a lifetime.
7.In the human brain, the areas that control breathing also control libido.
8.The human tongue has about 9,000 taste buds, but this number decreases as we age.
9.A person's fingerprint is unique, even if it's a twin.
10.The human brain can survive without oxygen for 5-10 minutes, but after a few minutes, the brain starts to be damaged.
11.The human liver is the only major organ that can be completely regenerated.
12.The human skeletal system is completely renewed every 10 years.
13.The human heart has four atria and ventricles, but only two are working and the other two are spare.
14.The surface area of a person's lungs is large enough to cover a tennis court.
15.The human kidneys filter about 180 litres of blood every day to remove waste and excess water from the body.
16.Human saliva contains a substance called salivary protease, which breaks down proteins in food.
17.There are cells called platelets in a person's blood that help blood clot and prevent excessive bleeding.
18.There is a substance on the human retina called rhodopsin, which helps the eye perceive light.
19.There is a structure in the human ear called the cochlea that converts sound into nerve signals that are transmitted to the brain.
20.There are cells in the human nose called olfactory receptors that help us smell smells.