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Adult head lice are gray, about ? inch long, and often have a tiny dot on their backs. A female can lay between 50 and 150 eggs within the several weeks that she is alive. They feed on human blood.
If all the neurons in the human body were lined up, they would stretch more than 600 miles.
When blood is exposed to air, it clots. Heparin allows the blood to come in direct contact with air without clotting.
Asthma cases in Americans are about 75% higher today than they were in 1980.
People who have myopia, or nearsightedness, are not able to see objects at a distance but only up close. It occurs when the cornea is either curved too steeply, the eye is too long, or both. This condition is progressive and worsens with time. More than 100 million people in the United States are nearsighted, but only 20% of those are born with the condition. Diet, eye exercise, drug therapy, and corrective lenses can all help manage nearsightedness.