Final answer:
Angiotensin II, or Ang II, activates several mechanisms, including stimulating aldosterone secretion from the adrenal cortex, which increases sodium and water reabsorption in the kidneys. This, in turn, raises blood volume and pressure. Ang II also acts on the NHE3 transporter in the proximal tubule to promote Na+ and HCO3− reabsorption.
Step-by-step explanation:
What does Ang II activate besides thirst, vasoconstriction, and ADH?
Angiotensin II, or Ang II, activates a variety of physiological mechanisms beyond thirst, vasoconstriction, and the stimulation of antidiuretic hormone (ADH). One of its key roles is to stimulate the release of aldosterone from the adrenal cortex. This hormone promotes the reabsorption of sodium (Na+) in the collecting ducts of the kidneys, leading to water reabsorption, increased blood volume, and consequently increased blood pressure. Ang II also influences the thirst mechanism by activating the thirst center in the hypothalamus, which encourages fluid intake, further impacting blood volume and pressure.
As for the multiple-choice options provided, Ang II is known to promote reabsorption of Na+ and bicarbonate (HCO3−) in the nephrons through the activity of NHE3 in the proximal tubule. This process contributes to maintaining blood pressure and volume homeostasis. In addition, Aldosterone, stimulated by Ang II, enhances the reabsorption of Na+ and subsequently water in the distal tubules and collecting duct, not directly through aquaporins but by increasing the sodium gradient, which encourages osmotic water flow.