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Did you know?
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.
Did you know?
Sperm cells are so tiny that 400 to 500 million (400,000,000–500,000,000) of them fit onto 1 tsp.
Did you know?
There are 20 feet of blood vessels in each square inch of human skin.
Did you know?
Nearly 31 million adults in America have a total cholesterol level that is more than 240 mg per dL.
Did you know?
After a vasectomy, it takes about 12 ejaculations to clear out sperm that were already beyond the blocked area.