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When blood is exposed to air, it clots. Heparin allows the blood to come in direct contact with air without clotting.
In 1844, Charles Goodyear obtained the first patent for a rubber condom.
More than 150,000 Americans killed by cardiovascular disease are younger than the age of 65 years.
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.
Hippocrates noted that blood separates into four differently colored liquids when removed from the body and examined: a pure red liquid mixed with white liquid material with a yellow-colored froth at the top and a black substance that settles underneath; he named these the four humors (for blood, phlegm, yellow bile, and black bile).