Introduction:
The body’s water content is regulated so that the total volume of water in the body remains constant. Thus, the volume of water taken into the body is equal to the volume lost each day.

Answer to Problem 1RAC
The correct answer is an option (a). The levels of angiotensin II increase.
Explanation of Solution
Explanation/justification for the correct answer:
Option (a). The levels of angiotensin II increase. The juxtaglomerular apparatus stimulates the sensation of thirst by responding to lower blood pressure by releasing renin. Renin than stimulate the formation of angiotensin ii, which leads to the secretion of aldosterone. Aldosterone increase vasoconstriction. That complete process stimulates the sensation of thirst. So, the correct answer is an option (a).
Explanation for incorrect answer:
Option (b). The osmolality of the blood decreases. It is an incorrect option because an increase in extracellular fluid or blood osmolality leads to a sensation of thirst. It is detected by the specialized cells in the supraoptic nucleus that initiates neural circuit activity.
Option (c). Blood pressure increases. This is a wrong statement because a decrease in blood pressure stimulates the sensation of thirst. It is detected by the baroreceptors, which send the action potential to the brain through a sensory neuron.
Option (d). Renin secretion decreases. The decrease in blood pressure does not stimulate the thirst sensation. The decrease in renin secretion also decreases the formation of angiotensin and aldosterone, which is responsible for thirst sensation. So, this is an incorrect answer.
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Chapter 27 Solutions
Seeley's Anatomy & Physiology
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