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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.
In the United States, an estimated 50 million unnecessary antibiotics are prescribed for viral respiratory infections.
Amoebae are the simplest type of protozoans, and are characterized by a feeding and dividing trophozoite stage that moves by temporary extensions called pseudopodia or false feet.
When blood is exposed to air, it clots. Heparin allows the blood to come in direct contact with air without clotting.
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.