Question

Volume of urine is regulated by
A. Aldosterone
B. Aldosterone and testosterone
C. ADH
D. Aldosterone and ADH

Answer 1

Hint: Several hormones help in maintaining body fluid homeostasis. Hormones that are secreted by the hypothalamus and the adrenal gland helps in maintaining the volume and concentration of the urine.

Complete answer:
Antidiuretic hormone or ADH is secreted by the neurohypophysis or the posterior part of the hypothalamus. ADH is also known as vasopressin. It performs two major functions: retain water in the body and constriction of blood vessels. Vasopressin increases water reabsorption in the collecting ducts of the nephrons and makes urine hypertonic. The filtrate is isotonic to blood plasma in proximal convoluted tubule (PCT), the filtrate becomes hypertonic to blood plasma in the descending limb of the loop of Henle, and the filtrate becomes hypotonic in the ascending loop of Henle. In the distal convoluted tubule (DCT), ADH (antidiuretic hormone) makes the filtrate isotonic to blood plasma.
ADH triggers the secretion and release of aldosterone that helps in increasing sodium ion concentration in blood. The increased concentration helps in increasing blood osmotic potential which increases water reabsorption in the collecting tubule and therefore, urine is released in the concentrated form.

Hence, the correct answer is option D.

Note: Aldosterone and Antidiuretic hormone (ADH) acts on the collecting ducts of nephrons. They have water reabsorptive functions to regulate urine volume and concentration. They increase fluid retention in the kidney. Their net effect decreases the volume of urine which increases the osmolarity of the urine.