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If all the neurons in the human body were lined up, they would stretch more than 600 miles.
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.
Asthma cases in Americans are about 75% higher today than they were in 1980.
Long-term mental and physical effects from substance abuse include: paranoia, psychosis, immune deficiencies, and organ damage.
Astigmatism is the most common vision problem. It may accompany nearsightedness or farsightedness. It is usually caused by an irregularly shaped cornea, but sometimes it is the result of an irregularly shaped lens. Either type can be corrected by eyeglasses, contact lenses, or refractive surgery.