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Your skin wrinkles if you stay in the bathtub a long time because the outermost layer of skin (which consists of dead keratin) swells when it absorbs water. It is tightly attached to the skin below it, so it compensates for the increased area by wrinkling. This happens to the hands and feet because they have the thickest layer of dead keratin cells.
Everyone has one nostril that is larger than the other.
The heart is located in the center of the chest, with part of it tipped slightly so that it taps against the left side of the chest.
Throughout history, plants containing cardiac steroids have been used as heart drugs and as poisons (e.g., in arrows used in combat), emetics, and diuretics.
There are over 65,000 known species of protozoa. About 10,000 species are parasitic.