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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.
The average human gut is home to perhaps 500 to 1,000 different species of bacteria.
The lipid bilayer is made of phospholipids. They are arranged in a double layer because one of their ends is attracted to water while the other is repelled by water.
If all the neurons in the human body were lined up, they would stretch more than 600 miles.
In the United States, an estimated 50 million unnecessary antibiotics are prescribed for viral respiratory infections.