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Author Question: Ideas that repeat what has already been said or include unrelated information may still be used to ... (Read 21 times) |
Hippocrates noted that blood separates into four differently colored liquids when removed from the body and examined: a pure red liquid mixed with white liquid material with a yellow-colored froth at the top and a black substance that settles underneath; he named these the four humors (for blood, phlegm, yellow bile, and black bile).
The human body produces and destroys 15 million blood cells every second.
Bacteria have flourished on the earth for over three billion years. They were the first life forms on the planet.
The immune system needs 9.5 hours of sleep in total darkness to recharge completely.
Not getting enough sleep can greatly weaken the immune system. Lack of sleep makes you more likely to catch a cold, or more difficult to fight off an infection.