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More than 2,500 barbiturates have been synthesized. At the height of their popularity, about 50 were marketed for human use.
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 first documented use of surgical anesthesia in the United States was in Connecticut in 1844.
Approximately one in three babies in the United States is now delivered by cesarean section. The number of cesarean sections in the United States has risen 46% since 1996.
Blood is approximately twice as thick as water because of the cells and other components found in it.