AP BIOLOGY

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ANIMAL PHYSIOLOGY

OSMOREGULATION

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
Your hypothalamus detects increased blood osmolarity. It signals the pituitary gland to secrete ADH which inserts aquaporins into the descending loop of henle. This response would lead to:
A
Increased water re absorption into the blood.
B
Decreased water re absorption into the blood.
C
Increased recycling of ions from blood.
D
Decreased blood pressure.
Explanation: 

Detailed explanation-1: -ADH is stored in neurons within the hypothalamus. These neurons express osmoreceptors that are exquisitely responsive to blood osmolarity and respond to changes as little as two mOsm/L. [2] Therefore, slight elevations in osmolarity result in the secretion of ADH.

Detailed explanation-2: -Antidiuretic hormone (ADH, or vasopressin): ADH helps regulate the water balance in your body by controlling the amount of water your kidneys reabsorb while they’re filtering wastes out of your blood.

Detailed explanation-3: -Increased blood osmolarity, sensed by osmoreceptors within the hypothalamus, activates release of vasopressin (also called antidiuretic hormone [ADH]) from the posterior pituitary.

Detailed explanation-4: -Increased osmolarity increases ADH secretion, leading to reabsorption of water. Salt can be excreted in excess of water, leading to a return toward normal plasma osmolarity.

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