Answer to Question 1
Thirst and satiety influence water intake in response to changes sensed by the mouth, hypothalamus, and nerves. When water intake is inadequate, the blood becomes concentrated (having lost water but not the dissolved substances within it), the mouth becomes dry, and the hypothalamus initiates drinking behavior. When water intake is excessive, the stomach expands and stretch receptors send signals to stop drinking. Similar signals are sent from receptors in the heart as blood volume increases.
When too much water is lost from the body and not replaced, dehydration develops. A first sign of dehydration is thirst, the signal that the body has lost some fluid. If a person is unable to obtain water or, as in many elderly people, fails to perceive the thirst message, the symptoms of dehydration may progress rapidly from thirst to weakness, exhaustion, and deliriumand end in death if not corrected. Notice that an early sign of dehydration is fatigue; keep that in mind when considering caffeinated beverages for an afternoon pick-me-up and choose water instead. Dehydration develops with either inadequate water intake or excessive water losses.
Answer to Question 2
When too much water is lost from the body and not replaced, dehydration develops. A first sign of dehydration is thirst, the signal that the body has lost some fluid. If a person is unable to obtain water or, as in many elderly people, fails to perceive the thirst message, the symptoms of dehydration may progress rapidly from thirst to weakness, exhaustion, and deliriumand end in death if not corrected. Notice that an early sign of dehydration is fatigue; keep that in mind when considering caffeinated beverages for an afternoon pick-me-up and choose water instead. Dehydration develops with either inadequate water intake or excessive water losses.
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