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Bacteria have flourished on the earth for over three billion years. They were the first life forms on the planet.
The familiar sounds of your heart are made by the heart's valves as they open and close.
In ancient Rome, many of the richer people in the population had lead-induced gout. The reason for this is unclear. Lead poisoning has also been linked to madness.
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.
More than 4.4billion prescriptions were dispensed within the United States in 2016.
![Vasectomy. (a) Vas deferens is located within the spermatic cord on both sides. (b) A small incision](https://biology-forums.com/gallery/47/medium_14755_16_10_12_12_27_39_94332233.jpeg)
![After all valves have been properly measured and adjusted as necessary, start the reassembly process ...](https://biology-forums.com/gallery/29/medium_548020_30_05_17_4_42_32_2975329.png)