Control of Renal Blood Flow

Question 1

What is clearance of PAH used for?

Answer 1

Measuring renal plasma flow.

Question 2

How to calculate RBF?

Answer 2

RBF = RPF/ (1-Hct)

Question 3

Two main categories regulation of renal blood flow?

Answer 3

Vascular and Non-Vascular

Question 4

Where in the vasculature is RBF regulated?

Answer 4

Afferent and Efferent arterioles.

Question 5

Effect of Constricting/Relaxing Afferent Arteriole

Answer 5

Constrict: Decrease Renal Blood Flow, Decrease GFR
Relax: Increase Renal Blood Flow, Increase GFR

Question 6

Filtration Fraction Definition and Equation

Answer 6

The percentage of delivered plasma that is filtered at the capillary. FF=GFR/RPF

Question 7

Effect of Constricting/Relaxing Efferent Arteriole

Answer 7

Constrict: Decrease Renal Blood Flow, Increase Filtration Fraction, Increase GFR.
Relax: Increase Renal Blood Flow, Decrease Filtration Fraction, Decrease GFR.

Question 8

How does FF affect proximal tubule reabsorption?

Answer 8

Increasing FF will increase hydrostatic pressure of the glomerular capillary, which will cause an increase in osmotic pressure of the glomerular capillary, which will increase the osmotic pressure of the peritubular capillary. This will drive reabsorption of H2O.

Question 9

Effect of Sympathetic Output on Renal Vasculature, RBF, and GFR

Answer 9

Constriction of afferent and efferent arterioles.
Decrease in RBF.
No change in GFR (maybe a little reduced).

Question 10

Effect of AngII on Renal Vasculature

Answer 10

Constriction of afferent and efferent arterioles, with a slight preference for efferent.
Decrease in RBF
No change in GFR (maybe a little reduced).

Also causes mesangial cell contraction

Question 11

Effect of ANP on Renal Vasculature

Answer 11

Dilation of afferent arteriole, constriction of efferent arteriole.
No change in RBF (opposite effects).
GFR increases.

Question 12

Affect of Histamine on Renal Vasculature

Answer 12

Dilation of afferent and efferent arterioles.
RBF increases.
No change in GFR.

Question 13

Affect of EDRF/NO on Renal Vasculature

Answer 13

Afferent dilation only.
No change in RBF.
Increased GFR.

Question 14

Does ADH have an effect on renal vasculature?

Answer 14

Not really.

Question 15

Effect of Endothelin on Renal Vasculature

Answer 15

Constriction of afferent and efferent arterioles (preference for afferent).
RBF decreases.
GFR decreases.

Question 16

Effect of PGE2 and PGI2 on Renal Vasculature

Answer 16

Dilation of afferent arterioles.
RBF increases.
GFR increases.

Question 17

Nonvascular regulation of RBF and GFR

Answer 17

Mesangial cell contraction, maybe podocyte contraction?

Question 18

What does mesangial cell contraction do to RBF and GFR?

Answer 18

Contraction of mesangial cells causes basement membranes to contract, reducing SA, which decreases Kf, and decreases GFR.

Question 19

Autoregulation of GFR and RBF

Answer 19

When BP rises, the afferent capillary will constrict (increasing renal vascular resistance) to maintain RBF and GFR. Controlled by NO, myogenic mechanism, but mostly tubuloglomerular feedback.

Question 20

Myogenic mechanism of autoregulation

Answer 20

As renal arterioles get stretched, they will contract with greater force. This is a passive process.

Question 21

Tubuloglomerular feedback mechanism of autoregulation

Answer 21

Increase in GFR will cause an increase in tubular flow. Flow past macula densa cells increases, causes release of adenosine onto afferent arteriole causing constriction.