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Human kidneys will clean about 1 million gallons of blood in an average lifetime.
Pope Sylvester II tried to introduce Arabic numbers into Europe between the years 999 and 1003, but their use did not catch on for a few more centuries, and Roman numerals continued to be the primary number system.
Every 10 seconds, a person in the United States goes to the emergency room complaining of head pain. About 1.2 million visits are for acute migraine attacks.
Asthma cases in Americans are about 75% higher today than they were in 1980.
For about 100 years, scientists thought that peptic ulcers were caused by stress, spicy food, and alcohol. Later, researchers added stomach acid to the list of causes and began treating ulcers with antacids. Now it is known that peptic ulcers are predominantly caused by Helicobacter pylori, a spiral-shaped bacterium that normally exist in the stomach.
![Examples of four different types of cells from the body. Although each cell has a cell membrane, nuc](https://biology-forums.com/gallery/47/medium_14755_16_09_12_5_52_12_8537838.jpeg)
![Photograph of the flea that transmits Yersinia pestis to cause bubonic plague, called the oriental r](https://biology-forums.com/gallery/47/medium_14755_11_11_12_7_20_12_100441848.jpeg)