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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.
The first-known contraceptive was crocodile dung, used in Egypt in 2000 BC. Condoms were also reportedly used, made of animal bladders or intestines.
Patients who cannot swallow may receive nutrition via a parenteral route—usually, a catheter is inserted through the chest into a large vein going into the heart.
The average adult has about 21 square feet of skin.
The longest a person has survived after a heart transplant is 24 years.