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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.
More than 30% of American adults, and about 12% of children utilize health care approaches that were developed outside of conventional medicine.
Egg cells are about the size of a grain of sand. They are formed inside of a female's ovaries before she is even born.
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.