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IgA antibodies protect body surfaces exposed to outside foreign substances. IgG antibodies are found in all body fluids. IgM antibodies are the first type of antibody made in response to an infection. IgE antibody levels are often high in people with allergies. IgD antibodies are found in tissues lining the abdomen and chest.
The immune system needs 9.5 hours of sleep in total darkness to recharge completely.
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.
If you could remove all of your skin, it would weigh up to 5 pounds.
According to research, pregnant women tend to eat more if carrying a baby boy. Male fetuses may secrete a chemical that stimulates their mothers to step up her energy intake.