13. Renal plasma flow (RPF), filtration fraction

Question 1

Renal plasma flow: determination:

Answer 1

The determination of the plasma amount flowing through the kidney (RPF) is based on the Flick-principle (law of conservation of matter):

Question 2

Renal plasma flow: Flick-principle

Answer 2

The amount of substance entering the kidney on the arterial side per unit time, must be equal to the sum of the amounts of the substance leaving the kidney with the renal vein and with the urine.

Question 3

Renal plasma flow: what does is measure

Answer 3

measures the clearance of any substance that is both filtered and completely excreted- such that none remains in the outgoing renal vein, can be used to determine the RPF. Such substance is the p- aminohippuric acid (PAH), which is both filtered and secreted.

Question 4

Renal plasma flow: equation

Answer 4

Pa x RPF = (Pv x RPF) + (U + V)

Question 5

Renal plasma flow: equation explain

Answer 5

Pa x RPF = (Pv x RPF) + (U + V)
RPF= renal plasma flow
Pa = Arterial substance concentration
Pv= venous substance concentration
U= substance concentration in the urine
V= rate of urine production

Question 6

Filtration fraction: how is it regulated

Answer 6

This is regulated by the adaptive contraction of the efferent arteriole, and the tubulo-glomerular feedback.

Question 7

Filtration fraction: how is it regulated: step 1

Answer 7

The blood pressure increases: moygenic mechanism

Question 8

Filtration fraction: how is it regulated step 1: how

Answer 8

To rise the blood pressure the afferent arteriole
answers by vasoconstriction (Bayliss-effect, and
vasodilation of efferent arteriole.

Question 9

Filtration fraction: how is it regulated: step 2

Answer 9

The blood pressure decreases: myogenic
mechanism

Question 10

Filtration fraction: how is it regulated: step 2: how

Answer 10

To the fall of blood pressure, the afferent arteriole reacts with vaso-dialtion, the efferent reacts with vasoconstriction