Question

In the chart showing regulation of urine formation what is indicated by P, Q, R, S?

• A. P = Increases $H_{2}O$ in the body, Q = Hypothalamus, R = Inhibits secretion of ADH, S = Inhibits reabsorption from posterior region of tubule
• B. P = Decreases $H_{2}O$ in body, Q = Hypothalamus, R = ADH secreted, $S=H_{2}O$ is reabsorbed from posterior part of tubule
• C. P = Decreases $H_{2}O$ in body, Q = Hind brain, R = Starts secretion of ADH, S = Reabsorption of H2O from anterior region of tubule
• D. None of above

Answer 1

The correct option is B P = Decreases $H_{2}O$ in body, Q = Hypothalamus, R = ADH secreted, $S=H_{2}O$ is reabsorbed from posterior part of tubule

ADH, or vasopressin, is synthesized in the hypothalamus. The hormone is transported down the axons, in vesicles to the posterior pituitary where the hormones are stored. Secretion of ADH is highly sensitive to water balance. Once secreted, ADH causes water retention in the kidneys.
So, the correct sequence is :
P = Decreases $H_{2}O$ in body, Q = Hypothalamus, R = ADH secreted, $S=H_{2}O$ is reabsorbed from posterior part of tubule