RBF/GFR (DSA + Lecture)

Question 1

What is the Tamm-Horsefall protein? Why is it seen in urine?

Answer 1

Protein produced by thick ascending loop of henle

Surpasses filtration of proteins in PCT, so ends up in urine

Question 2

What two molecules are responsible for the negative charge of biogel? Where is biogel found?

Answer 2

Found over the fenestrations of capillary endothelium (in lumen)

Heparin Sulfates and Hyaluronin

Question 3

What are three molecular fillers found in the filtration diaphragm?

Which one is specific to renal?

Answer 3

Cadherin, actin, and Nephrin

Nephrin is specific to renal

Question 4

Role of molecular fillers?

Answer 4

Provide a physical barrier against larger molecules

Question 5

What are 3 characteristics indicate a damaged filtration barrier?

Answer 5

Hypercellularity

Thickened Basement membrane (increases distance for filtration)

Glomerulosclerosis (increased extracellular tissue, so decreased SA for filtration)

Question 6

Which part of the kidney has coiled blood vessels/ intertwined tubules?

Answer 6

Cortex

Question 7

What 5 criteria is are necessary for a substance to be able to measure GFR?

Answer 7

1. Can’t be broken down or metabolized by kidney
2. Shouldn’t be reabsorbed or secreted
3. Shouldn’t alter GFR
4. Should have a stable plasma concentration
5. Should be able to freely diffuse across the glomerulus

Question 8

What happens to oncotic pressure of the efferent arteriole when GFR Increases?

Answer 8

It increases

Question 9

What receptors lead to vasoconstriction of afferent arterioles?

Answer 9

Sympathetic stimulation of a1 receptors

Question 10

What receptors lead to increased RAAS activation by the JGA cells?

Answer 10

Sympathetic stimulation of B1 receptors

Question 11

What receptors lead to increased N/K ATPase functioning

Answer 11

Sympathetic stimulation of a1 receptors

(Results in more reabsorption of Na) –> more retention of water and increased blood volume

Question 12

Immediate effects of sympathetic stimulation

Answer 12

• Vasoconstriction of afferent arterioles
• RAAS stimulation
• Decreased GFR
• Decreased RBF
• Increased Thirst
• Increased BP

Question 13

Long term effects of sympathetic stimulation

Answer 13

• Decreased urine output
• Increased water intake
• Decreased Na secretion

Question 14

What is a normal BUN:Creatine Ratio?

Answer 14

10:1

Post renal problem

Question 15

What is a High BUN:Creatine Ratio?

Answer 15

20:1

Pre-renal problem

Question 16

What is a Low BUN:Creatine Ratio?

Answer 16

10:1

Intrarenal problem

Question 17

Dilation of afferent arteriole

Answer 17

IN GFR

IN RBF

Question 18

General rule with GFR/ RBF/ arterioles?

Answer 18

With Afferent: Both RBF and GFR will move in same direction

With Efferent: GFR and RBF move in opposite directions

Hydrostatic pressure moves in same direction as RBF
Oncotic pressure of efferent arteriole moves in same direction as GFR

Question 19

Constriction of afferent arteriole

Answer 19

DEC GFR

DEC RBF

Question 20

Constriction of efferent arteriole

Answer 20

INC GFR

DEC RBF

Question 21

Dilation of efferent arteriole

Answer 21

DEC GFR

INC RBF

Question 22

What causes constriction of efferent arterioles?

Answer 22

RAAS system

AGT 2

Question 23

What causes constriction of afferent arterioles?

Answer 23

Sympathetic Nervous system

Question 24

What causes vasodilation of afferent arterioles?

Answer 24

NO
Prostaglandins
Dopamine
ANP
Bradykinin

Question 25

Glomerulartubular Balance

Answer 25

GFR impacts tubule conditions Increase in GFR = Increase in reabsorption in tubules

Question 26

What are the 3 mechanisms of GT Balance?

Answer 26

1. Change in pressure 2. Change in flow rate 3. GFR and flow rate impact microvilli sheer stress

Question 27

What is autoregulation?

Answer 27

Allows for RBF and GFR to be maintained within narrow limits

Question 28

What is the myogenic response of autoregulation?

Answer 28

Increased pressure results in contractions (local reflex) (since blood vessels resist stretch) Results in a decreased GFR

Question 29

What is TG Feedback?

Answer 29

Tubule impacts GFR! Feedback loop between: 1. Macula densa cells= detect Na+ changes 2. JGA cells = Renin secretion 3. Mesangial cells= Transduction of signal

Question 30

Steps of TG Feedback with Increased Perfusion Pressure

Answer 30

1. Increased Na+ = stimulation of macula densa 2. Influx of Na triggers ATP/Adenosine to be released 3. ATP binds to its receptor (PX2) and Adenosine binds to A1 receptor on VSM cells. 4. This binding will allow calcium signaling ---> decrease in GFR: afferent will constrict

Question 31

Steps of TG Feedback with Decreased Perfusion Pressure

Answer 31

1. Decreased NA+ 2. Macula Densa signals to JGA Cells 3. JGA Cells secrete renin 4. Activation of RAAS pathway 5. Efferent arterioles constrict due to AGT2 6. Increase in GFR