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There are 60,000 miles of blood vessels in every adult human.
Vampire bats have a natural anticoagulant in their saliva that permits continuous bleeding after they painlessly open a wound with their incisors. This capillary blood does not cause any significant blood loss to their victims.
Nearly 31 million adults in America have a total cholesterol level that is more than 240 mg per dL.
There are more sensory neurons in the tongue than in any other part of the body.
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.