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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.
People often find it difficult to accept the idea that bacteria can be beneficial and improve health. Lactic acid bacteria are good, and when eaten, these bacteria improve health and increase longevity. These bacteria included in foods such as yogurt.
Human kidneys will clean about 1 million gallons of blood in an average lifetime.
Autoimmune diseases occur when the immune system destroys its own healthy tissues. When this occurs, white blood cells cannot distinguish between pathogens and normal cells.
The average adult has about 21 square feet of skin.