Question

Concentration of urine is controlled by:
A) ACTH
B) MSH
C) ADH
D) Oxytocin

Answer 1

Hint: We know that the factors that are responsible for the formation of concentrated urine are a loop of Henle and antidiuretic Hormone. The loop of Henle creates a negative or low water potential in the medulla tissues to absorb more water from the fluids present in the collecting duct.

Complete answer:
As we know that the antidiuretic hormone (ADH) is a hormone that helps the kidneys maintain body water balance. This hormone causes water reabsorption by causing aquaporins, or water channels, to be introduced into the membranes of kidney tubules. These channels transport solute-free water via tubular cells before returning to circulation. As a result, the plasma osmolarity decreases, while the urine osmolarity increases.

The permeability of the distal convoluted tubule and collecting duct to water is increased by ADH, which is ordinarily impervious to water. It is primarily responsible for controlling and balancing the amount of water in the blood, as well as enhancing glomerular blood flow by raising blood pressure. The tightening of blood arteries caused by higher ADH concentrations raises blood pressure. The ADH is activated by the pituitary glands posterior part. Wastes such as urea, ammonia, uric acid are generally excreted in the urine. The potassium, sodium, and calcium ions are also excreted out of the body in the urine. Humans are called as ureotelic as the major component in urine is urea

Therefore, the correct answer is option C.

Note: Remember that concentrated urine means that the concentration of the solute is more as compared to the water. Solutes present are dissolved particles, such as sugars, salts, and proteins. ADH triggers the secretion and release of aldosterone that helps in increasing sodium ion concentration in blood.