Question

What transport processes, in which tubules, are regulated by Angiotensin II and Aldosterone? If it can promote hypertension, then why do animals need the RAAS? What conditions activate the RAAS (what real-world events can drive the variables regulated below the set-point)?

a. Angiotensin II regulates active transport in the distal tubule; Aldosterone in the proximal tubule; RAAS needed for fluid balance; activated by dehydration
b. Angiotensin II regulates reabsorption in the loop of Henle; Aldosterone in the collecting duct; RAAS needed for sodium balance; activated by excess sodium intake
c. Angiotensin II regulates reabsorption in the proximal tubule; Aldosterone in the distal tubule; RAAS needed for blood pressure regulation; activated by low blood pressure
d. Angiotensin II regulates filtration in the glomerulus; Aldosterone in the loop of Henle; RAAS needed for pH balance; activated by high blood pressure

Answer 1

Angiotensin II regulates reabsorption in the proximal tubule, while Aldosterone regulates sodium reabsorption in the distal tubule and collecting ducts. The RAAS system is necessary for blood pressure regulation and is activated by low blood pressure or low blood volume, such as during dehydration.

Step-by-step explanation:

The transport processes regulated by Angiotensin II and Aldosterone occur in different parts of the renal tubules. Angiotensin II acts as a potent vasoconstrictor, but it also stimulates the reabsorption of sodium in the proximal tubule. Aldosterone, on the other hand, increases sodium reabsorption in the distal tubule and the collecting ducts, leading to water retention and, consequently, an increase in blood pressure.

The renin-angiotensin-aldosterone system (RAAS) is crucial for blood pressure regulation. It is activated under real-world conditions such as low blood pressure or low blood volume, which can result from scenarios like dehydration. These events decrease the set-point of variables that RAAS regulates, triggering its activation. The system, when activated, can promote hypertension if not properly regulated, but it is essential for maintaining fluid and electrolyte balance within the body.