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When blood is deoxygenated and flowing back to the heart through the veins, it is dark reddish-blue in color. Blood in the arteries that is oxygenated and flowing out to the body is bright red. Whereas arterial blood comes out in spurts, venous blood flows.
When Gabriel Fahrenheit invented the first mercury thermometer, he called "zero degrees" the lowest temperature he was able to attain with a mixture of ice and salt. For the upper point of his scale, he used 96°, which he measured as normal human body temperature (we know it to be 98.6° today because of more accurate thermometers).
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.
Fungal nail infections account for up to 30% of all skin infections. They affect 5% of the general population—mostly people over the age of 70.
Every flu season is different, and even healthy people can get extremely sick from the flu, as well as spread it to others. The flu season can begin as early as October and last as late as May. Every person over six months of age should get an annual flu vaccine. The vaccine cannot cause you to get influenza, but in some seasons, may not be completely able to prevent you from acquiring influenza due to changes in causative viruses. The viruses in the flu shot are killed—there is no way they can give you the flu. Minor side effects include soreness, redness, or swelling where the shot was given. It is possible to develop a slight fever, and body aches, but these are simply signs that the body is responding to the vaccine and making itself ready to fight off the influenza virus should you come in contact with it.