Renal Endocrinology B&B

Question 1

what are the 3 stimulators of renin release from the JG apparatus?

Answer 1

1. low perfusion pressure (sensed by afferent arteriole)
2. Low NaCl delivery (sense by macula densa)
3. Sympathetic activation (beta1 receptors)

Question 2

describe how angiotensin II increases Na+ and H2O reabsorption via the “capillary effect”

Answer 2

capillary effect: efferent arteriole constriction decreases hydrostatic pressure and increases oncotic pressure within the capillary

net result is that efferent arteriole constriction by AII leads to increased NaCl reabsorption in the proximal tubule (creates a favorable gradient)

Question 3

what are the 3 overall effects of aldosterone?

Answer 3

1. increased Na+ and H2O reabsorption (increased effective circulating volume)
2. increased K+ excretion (via principal cells)
3. increased H+ excretion (via intercalated cells)

Question 4

What is the net effect of parathyroid hormone?

Answer 4

PTH: secreted by chief cells of parathyroid gland, stimulated by low plasma [Ca2+]

—> increased Ca2+ reabsorption in DCT
—> decreased PO4 reabsorption in PCT
—> increased 1,25-OH2 vitamin D production in PCT

Question 5

where is erythropoietin made in the kidneys?

Answer 5

interstitial cells of peritubular capillary

*decreased production in renal failure —> normocytic anemia

Question 6

where is dopamine synthesized in the kidneys and what effect on kidney function does it have?

Answer 6

dopamine - synthesized in proximal tubule

—> dilates afferent and efferent arterioles (at low doses) —> increased RPF, no change in GFR

—> promotes natriuresis