Renal Physiology

Question 0

name to markers for GFR (note, one is naturally made by humans)

Answer 0

creatinine (resulting from normal metabolism of creatinine phosphate in muscle) and inulin (derived from Jerusalem artichoke)

Question 1

What is normal GFR?

Answer 1

normal glomerular filtration rate is 125mL/min or 180L/day

Question 2

What percentage of cardiac output do the kidneys receive?

Answer 2

20% or, in other words, 1L/min

Question 3

what is the kidney’s response to a rise in renal blood flow?

Answer 3

the kidney responds to an increase in renal blood flow by increasing resistance of afferent arteriole (and slightly decreasing resistance of efferent arteriole)

Question 4

how does the kidney respond to a decrease in renal blood flow?

Answer 4

the kidney responds to a decrease in renal blood flow by decreasing resistance of afferent arterioles (and slightly increasing resistance of efferent arterioles)

Question 5

what in particular does the macula densa sense in order to regulate kidney function?

Answer 5

concentrations of Na and Cl in the lumen of the thick ascending limb (this allows the macula densa to indirectly sense changes in GFR, which is what usually causes rises in these ion concentrations)

Question 6

what is the main effect of angiotensin II

Answer 6

reduce blood flow, and thereby, GFR by

1. constricting renal artery, afferent arterioles, and efferent arterioles
2. contracting mesangial cells (specialized smooth muscle cells that surround vessels in the kidney)
3. increased sensitivity (increased responsiveness of afferent arterioles to macula densa signal)

Question 7

what does the sympathetic nervous system do in response to high GFR

Answer 7

release norepinephrine which leads to constriction of arterioles and therefore lower RBF and GFR

Question 8

what does ADH (aka AVP or vasopressin) do?

Answer 8

increases water absorption in the collecting duct and increases vascular resistance

Question 9

what does ANP (atrial natriuretic peptide) do?

Answer 9

.