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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.
Nearly all drugs pass into human breast milk. How often a drug is taken influences the amount of drug that will pass into the milk. Medications taken 30 to 60 minutes before breastfeeding are likely to be at peak blood levels when the baby is nursing.
Drug abusers experience the following scenario: The pleasure given by their drug (or drugs) of choice is so strong that it is difficult to eradicate even after years of staying away from the substances involved. Certain triggers may cause a drug abuser to relapse. Research shows that long-term drug abuse results in significant changes in brain function that persist long after an individual stops using drugs. It is most important to realize that the same is true of not just illegal substances but alcohol and tobacco as well.
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).
The lipid bilayer is made of phospholipids. They are arranged in a double layer because one of their ends is attracted to water while the other is repelled by water.