Exam 1: RBF And GFR

Question 1

How much CO do the kidneys receive?

Answer 1

1/4 of the cardiac output

Question 2

How many liters of filtrate are formed per day?

Answer 2

180 liters

Question 3

What is the equation for filtration fraction (FF)?

Answer 3

GFR/RPF

Question 4

What is normal RBF?

Answer 4

1.1 L/min

Question 5

What is the equation to calculate Renal plasma flow (RPF)?

Answer 5

(1-Hct)(RBF)

Question 6

What are the vasoconstrictors to regulate RBF?

Answer 6

Sympathetic nerves via Alpha 2 receptors and Angiotensin II, ADH, ATP, and endothelin

Question 7

What are the vasodilators that work to increased RBF and GFR?

Answer 7

Atrial natriuretic peptide (ANP), glucocorticoids, NO, and prostaglandins

Question 8

What is autoregulation?

Answer 8

Constant blood flow and GFR though a range of arterial pressures

Question 9

What are the two mechanisms that contribute to autoregulation?

Answer 9

The myogenic mechanism and the tubuloglomerular feedback mechanism

Question 10

What is Tubuloglomerular feedback?

Answer 10

Increasing GFR increases NaCl delivery to the LOH, this is sensed by the macula densa which causes resistant to the afferent arteriole to increase thereby decreasing RBF and GFR

Question 11

What is Kf?

Answer 11

The filtration rate produced by each mmHm of net filtration pressure

Question 12

Tubuloglomerular feedback maintains the constancy of ** delivered to the **.

Answer 12

Salt

Distule tubule

Question 13

What are the main barriers to proteins in regards to glomerular filtration?

Answer 13

Basal lamina and filtration slits

Question 14

What is PGC?

Answer 14

Blood pressure in glomerular capillary, which is the driving force for GFR

Question 15

What is PBC?

Answer 15

Back pressure in Bowman’s capsule, which reduces GFR

Question 16

How are PGC and GFR related?

Answer 16

Directly, as PGC increases so does GFR

Question 17

When afferent and efferent arteriolar resistances increase, what is the effect on PGC and RBF?

Answer 17

No effect on PCG, but dramatic decrease in RBF

Question 18

What happens to PGC and RBF when afferent arteriolar resistances increase?

Answer 18

Both PGC and RBF decrease

Question 19

What happens to PGC and RBF when the efferent arteriolar resistances increases?

Answer 19

PGC increases and RBF decreases

Question 20

What do PGE2 and PGI2 do?

Answer 20

They vasodilator the afferent arterioles by reducing vasoconstriction produced by the SNS stimulation to maintain blood flow

Question 21

What do NSAIDs do to prostaglandins?

Answer 21

They inhibit the synthesis of prostaglandins by inhibiting the activity of COX1 and 2.

Question 22

What is tubular secretion?

Answer 22

When solutes go from the peritubular capillary to the tubular lumen

Question 23

What equation describes GFR?

Answer 23

Starling equation:

GFR= Kf (Pgc -Pbc) - (πgc -πbc)

Question 24

What is Pgc?

Answer 24

Blood pressure in the glomerular capillary (the driving force for GFR)

Question 25

What is Pbc?

Answer 25

The back pressure in Bowman’s capsule (reduces GFR)

Question 26

What is πgc?

Answer 26

Oncotic pressure in glomerular capillary blood (due to proteins being unable to cross the barrier and retards GFR)

Question 27

When does πgc increase?

Answer 27

AS plasma is diverted into Bowman’s capsule

Question 28

What is πbc?

Answer 28

The oncotic pressure in Bowman’s capsule, but its usually zero because there are not normally proteins in Bowman’s capsule

Question 29

Why is Angiotensins effect on GFR variable?

Answer 29

AT II constricts both afferent and efferent, but efferent is more sensitive. Low dose AT II will mostly affect efferent

Question 30

What is the equation for NFP?

Answer 30

NFP= (Pgc -Pibc) - (Pbc- Pigc)

Question 31

What happens to RBF and GFR with high concentrations of AT II?

Answer 31

Decreased GFR and RBF (both afferent and efferent arterioles are constricted)

Question 32

What happens to RBF and GFR in low doses of AT II?

Answer 32

GFR is unaffected and RBF is decreased (only efferent arteriole is constricted)