negative feedback

Negative feedback is the body's way of holding a level steady, and it has four steps. First a level moves away from normal — the body is short of water, or the glucose level in the blood falls. Then a gland releases its hormone: the pituitary releases ADH, or the pancreas releases glucagon. The hormone acts on its target organ and moves the level back toward normal — the kidneys take water back, or the liver releases glucose. And then the gland slows or stops releasing the hormone, because the change that started the loop is gone. The word "negative" describes that last step: the response cancels the change rather than adding to it. The exam usually asks about the ending, and the answer is that the gland slows or stops — a gland that kept releasing at the same rate would drive the level past normal instead of back to it.