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Author Question: In a reflex arc, the coordination between contraction of certain muscles and relaxation of others is ... (Read 83 times) |
There are more nerve cells in one human brain than there are stars in the Milky Way.
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).
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.
The average human gut is home to perhaps 500 to 1,000 different species of bacteria.
The familiar sounds of your heart are made by the heart's valves as they open and close.