Which Hormone Most Affects the Osmolarity of Blood

Question

Which hormone most affects the osmolarity of blood?
A) ADH
B) angiotensin II
C) PTH
D) ANP
E) epinephrine

Accepted Answer

ADH (antidiuretic hormone), also known as vasopressin, is the hormone that most affects the osmolarity of blood by regulating water reabsorption in the kidneys. ADH is released by the hypothalamus in response to changes in blood osmolarity (concentration of solutes) and acts on the kidneys to increase water reabsorption, leading to a more concentrated urine and higher blood volume and pressure. This helps maintain the osmolarity of blood within a narrow range and prevent dehydration.