For each of the following situations, describe the anticipated effect on blood pressure and the physiological basis of the response: (1) a high-salt diet, (2) a blow on the head that damages (disables) the vasomotor center, (3) an attack by a mugger, and (4) a hypothalamic tumor resulting in excess ADH production.
What will be an ideal response?
(1) A high-salt diet causes increased sodium in the blood, which increases total extracellular fluid volume. This leads to increased blood volume and blood pressure. (2) Damage to the vasomotor center will cause a loss of vasomotor tone and a drop in blood pressure because the vasomotor center is the integrating center for blood pressure control. (3) During the mugger attack, blood pressure would increase due to sympathetic nervous system stimulation (the fight-or-flight response) triggered by the hypothalamus. (4) Excess ADH production would cause an increase in blood pressure through increased water retention and therefore increased blood volume. ADH also stimulates vasoconstriction.
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