Question

How will the following cause the increase of vasopressin from the pituitary gland?

a) SHRINKING or SWELLING of osmoreceptor cells in the brain

b) INCREASE or DECREASE in plasma volume

c) POSITIVE or NEGATIVE sodium balance

Answer 1

Ans.a. Shrinkage of cells

b.Decreased plasma volume

c. Positive Sodium balance

Vasopressin or Antidiuretic hormone is secreted from posterior pituitary in response to increased plasma osmolarity or decreased plasma volume

It binds to receptors on cells in the collecting ducts of the kidney and promotes reabsorption of water back into the circulation.

Antidiuretic hormone stimulates water reabsorbtion by stimulating insertion of "water channels" or aquaporins into the membranes of kidney tubules. These channels transport solute-free water through tubular cells and back into blood, leading to a decrease in plasma osmolarity.