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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 liver is the only organ that has the ability to regenerate itself after certain types of damage. As much as 25% of the liver can be removed, and it will still regenerate back to its original shape and size. However, the liver cannot regenerate after severe damage caused by alcohol.
Throughout history, plants containing cardiac steroids have been used as heart drugs and as poisons (e.g., in arrows used in combat), emetics, and diuretics.
For high blood pressure (hypertension), a new class of drug, called a vasopeptidase blocker (inhibitor), has been developed. It decreases blood pressure by simultaneously dilating the peripheral arteries and increasing the body's loss of salt.
Human neurons are so small that they require a microscope in order to be seen. However, some neurons can be up to 3 feet long, such as those that extend from the spinal cord to the toes.