Question

The release of renin from the kidney plays an important role in maintaining a constant body Na+ content.

a) Explain why it is extremely important that total body Na+ content remains constant.

b) What causes the release of renin from the kidney?

c) Describe how the kidney regulates total body Na+ content.

Answer 1

a) Sodium is extremely important, that total body Na+ contents remain constant.

The total amount of sodium in the body affects the amount of fluid in the blood and around the cells.

Sodium and water balance are regulated by endocrine system.

Aldosterone causes kidneys to retain sodium and excrete potassium.As the Sodium is retained less urine is produced.

B)Renin is a proteolytic enzyme.When their is fall in GFR due to decresed blood pressure this decresed blood pressure causes decreases in blood flow to the kidney there is decrese in renal perfusion this stimuli cause increased release of Renin from juxtaglomerular cells of kidney.This renin causes increase in blood pressure through RAAS mechanism.

C)About 65-70 % of sodium is reabsorbed at the proximal convoluted tubule ,20-25 % reabsorbed at the loop of Henle, remaining is reabsorbed at distal nephron that is proximal convoluted tubule and collecting duct.When there is decrease in osmolarity in the body there is rekase of steroid hormone called aldosterone from zona glomerulosa cells of adrenal cortex.The aldosterone causes reabsorption of sodium from distal nephron.