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When blood is deoxygenated and flowing back to the heart through the veins, it is dark reddish-blue in color. Blood in the arteries that is oxygenated and flowing out to the body is bright red. Whereas arterial blood comes out in spurts, venous blood flows.
Egg cells are about the size of a grain of sand. They are formed inside of a female's ovaries before she is even born.
According to the Migraine Research Foundation, migraines are the third most prevalent illness in the world. Women are most affected (18%), followed by children of both sexes (10%), and men (6%).
There are over 65,000 known species of protozoa. About 10,000 species are parasitic.
The heart is located in the center of the chest, with part of it tipped slightly so that it taps against the left side of the chest.