Question

1.How do kidneys respond an increase in ADH?

2. what is the order of the blood vessels that carry blood to be filtrate to the kidneys from the renal artery to the peritubular capillaries?

3. what is countercurrent multiplication and where does it take place in the nephron?

Answer 1

Answer

1)

• ADH is anti-diuretic hormone released by posterior pituitary gland.
• ADH primarily acts on collecting ducts of the nephron.
• ADH causes installation of aquaporin channels, also called water cahnnels on the cell membrane of the cells in the wall of collecting duct.
• This makes the collecting duct permeable to water.
• Water follows osmotic gradient and moves out of collecting duct (reabsorption), into the peritubular capillaries.
• Hence, with increase in ADH, kidney increases water reabsorption and decreases urine formation.

2) The order of blood vessels :

1. Renal artery
2. Segmental artery
3. Interlobar artery
4. Arcuate artery
5. Interlobular artery
6. Afferent arteriole
7. Glomerular capillaries
8. Efferent arteriole
9. Peritubualr capillaries

3)

• Countercurrent multiplication is the process of establishing an osmotic gradient that allows water reabsorption from the renal tubules and formation of concentrated urine.
• Countercurrent multiplication takes place in loop of Henle of the nephron.
• This process is facilitated by segments of the loop having descending limb of the loop that is permable to water and ascending limb of the loop that is permable to solutes.