Question

Be sure you know the entire regulatory cascade of the RAAS from the variables regulated, to sensor, to integrator, to all hormones (and how they are activated and released), to effector tissues, to compensatory responses, to negative feedback.

Answer 1

The RAAS is a regulatory cascade involved in maintaining blood pressure, blood volume, and electrolyte balance. It starts with the sensing of variables by JG cells, which release renin as an integrator. Renin activates the RAAS leading to the release of hormones like angiotensin II and aldosterone, which act on effector tissues like the adrenal cortex and kidneys. Compensatory responses include sodium reabsorption and potassium excretion, increasing blood volume and pressure. Negative feedback inhibits renin release when blood volume and pressure are increased.

Step-by-step explanation:

The entire regulatory cascade of the RAAS:

1. Variables regulated: Blood pressure, blood volume, and electrolyte balance
2. Sensor: Juxtaglomerular (JG) cells of the afferent arteriole at the juxtaglomerular apparatus (JGA)
3. Integrator: Renin, an enzyme produced by the JG cells
4. Hormones: Renin activates the renin-angiotensin-aldosterone system (RAAS), which releases angiotensin I, angiotensin II, and aldosterone. Angiotensin II stimulates the release of aldosterone from the adrenal cortex
5. Effector tissues: Angiotensin II acts on the adrenal cortex to stimulate the release of aldosterone, which acts on the kidneys
6. Compensatory responses: Increased aldosterone levels cause sodium reabsorption and potassium excretion in the kidneys to increase blood volume and raise blood pressure
7. Negative feedback: Increased blood volume and blood pressure inhibit renin release, thus decreasing activation of the RAAS and aldosterone production.