Component 3.4 - Osmoregulation

Question 1

What is the receptor for osmoregulation?

Answer 1

The hypothalamus, because it has osmoreceptors that monitor the concentration of the blood plasma

Question 2

What is the effector in osmoregulation?

Answer 2

Posterior pituitary gland as it stores and releases ADH

Question 3

What does ADH do?

Answer 3

1) ADH increases the permeability of the plasma membranes of the collecting duct and distal convoluted tubule
2) ADH causes aquaporins to become incorporated in the plasma membranes
2) More water is absorbed by osmosis from the filtrate into the surrounding, hypertonic tissue fluid
3) Hence more water is reabsorbed from the medulla into the vasa recta

Question 4

Describe the features of the urine near the bottom of the collecting duct?

Answer 4

Has a concentration close to the concentration of the tissue fluid near the bottom of the loop, which is hypertonic to the general body fluids