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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).
In the United States, an estimated 50 million unnecessary antibiotics are prescribed for viral respiratory infections.
Blood in the urine can be a sign of a kidney stone, glomerulonephritis, or other kidney problems.
The ratio of hydrogen atoms to oxygen in water (H2O) is 2:1.
Prostaglandins were first isolated from human semen in Sweden in the 1930s. They were so named because the researcher thought that they came from the prostate gland. In fact, prostaglandins exist and are synthesized in almost every cell of the body.
![The functional structure of the peripheral nervous system. (A) Afferent or sensory neurons carry sen](https://biology-forums.com/gallery/47/medium_14755_27_08_12_4_56_12_8219264.jpeg)
![Urinometer. In this procedure, a urine sample and urinometer are placed within a tube, and the liqui](https://biology-forums.com/gallery/47/medium_14755_05_10_12_4_17_11_92921634.jpeg)