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There are over 65,000 known species of protozoa. About 10,000 species are parasitic.
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 senior population grows every year. Seniors older than 65 years of age now comprise more than 13% of the total population. However, women outlive men. In the 85-and-over age group, there are only 45 men to every 100 women.
The modern decimal position system was the invention of the Hindus (around 800 AD), involving the placing of numerals to indicate their value (units, tens, hundreds, and so on).
On average, someone in the United States has a stroke about every 40 seconds. This is about 795,000 people per year.