ADH And Osmoregulation

Question 1

What is osmoregulation?

Answer 1

The control of blood water potential

Question 2

Where are osmoreceptors located?

Answer 2

Hypothalamus

Question 3

Where is Antidiuretic Hormone released and what is its role?

Answer 3

• released from the pituitary gland
• controls the volume of water reabsorbed from the DCT and collecting duct by affecting cells permeability to water

Question 4

How does ADH affect the volume of concentrated urine produced?

Answer 4

Small volume is produced as ADH causes more water to be reabsorbed into the blood

Question 5

What happens if blood water potential decreases?

Answer 5

• osmoreceptors in the hypothalamus are stimulated
• impulses are sent to the posterior pituitary gland and ADH is released into the blood
• ADH binds to receptor proteins on the epithelial cells lining the DCT and collecting duct
• this causes aquaporins to be inserted into the membrane, which increases the DCT and collecting ducts permeability to water
• increased water moves out of the DCT init the capillaries through the aquaporins which raises the blood water potential back to normal
• this results in a decreased volume of urine being produced

Question 6

What happens is blood water potential increases?

Answer 6

• reduced stimulation of osmoreceptors
• so less ADH is released into the blood and the permeability of the DCT and collecting duct cells is reduced
• so less water is reabsorbed from the filtrate back into the blood so the water potential of the blood decreases back to normal
• a larger volume of dilute urine is produced