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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.
Signs of depression include feeling sad most of the time for 2 weeks or longer; loss of interest in things normally enjoyed; lack of energy; sleep and appetite disturbances; weight changes; feelings of hopelessness, helplessness, or worthlessness; an inability to make decisions; and thoughts of death and suicide.
Coca-Cola originally used coca leaves and caffeine from the African kola nut. It was advertised as a therapeutic agent and "pickerupper." Eventually, its formulation was changed, and the coca leaves were removed because of the effects of regulation on cocaine-related products.
Intradermal injections are somewhat difficult to correctly administer because the skin layers are so thin that it is easy to accidentally punch through to the deeper subcutaneous layer.
There are 20 feet of blood vessels in each square inch of human skin.