Question

2a.How did the addition of aldosterone affect urine volume (compared with baseline)? Can the reabsorption of solutes influence of water reabsorption in the nephron? Briefly explain. ANS:

b.How did the addition of ADH affect urine volume (compared with baseline)? Why did the addition of ADH also affect the concentration of potassium in the urine (compared with baseline)? ANS:

c.What is the principal determinant for the release of aldosterone from the adrenal cortex? ANS:

d.What is the principal determinant for the release of ADH from the posterior pituitary gland? Does ADH favor the formation of dilute or concentrated urine? Explain why. ANS:

Answer 1

2a.

Aldosterone is a hormone produced by adrenlgland present attached to kidneys. The hormone increases blood Na levels.= by absorbing more Na from the glomerular filtrate and preventing its loss. So, when aldosterone is released, na is absorbed form the kidney tules in to the blood increasing the blood Na levels. When the blood Na levels go up, water reabsorption also increases. Increase in water reabsorption will make the urine concentrated. This is how reabsorption of the Na will make the blood osmo concentration higher and hence results in more water reabsorption.

b.Addition AHDH increases the permeability of the DCT and CT to water. More water absorbing channels will come to the surface of the tubular cells resulting water reabsorption. Water reabsorption is always associated with the Na levels in blood. More Na reabsorption and more water absorption will result in the release of K in to the urine. Na reabsorption is closely linked to K release in to the glomerular filtrate . This lowers the K levels in blood.

c. Aldosterone release is influenced by Na levels in the blood. Decreased levels of Na will result in low osmotic pressure in blood. Because of this, angiotensin released in to blood stimulates adrenal gland to release aldosterone in to blood.

d.ADH release is mainly controlled by water levels in the body. ADH release increases the absorption of water from glomerular filtrate of DCT and CT in to the blood. This decreases urine volume and increases urine concentration.