Lecture 5-Renal Blood Flow And GFR

Question 1

Which type of nephron is the most abundant in kidney?

Answer 1

Cortical nephron

Question 2

What are the differences between cortical and juxtamedullary nephrons?

Answer 2

• cortical: short loop of Henle, lots of renin, rich sympathetic nerve innervation
• juxtamedullary: long loop of Henle, almost no renin, poor sympathetic nerve innervation

Question 3

What % of blood from the renal artery is filtered at any one time at the glomerulus?

Answer 3

20%

Question 4

What makes up the renal corpuscle?

Answer 4

Glomerulus and Bowman’s capsule

Question 5

True or false: proteins are small enough to be filtered by the glomerulus

Answer 5

FALSE - too large

Question 6

What are the three layers of the filtration barrier?

Answer 6

• capillary endothelium
• basement membrane
• podocytes

Question 7

What is the capillary endothelium permeable to?

Answer 7

Water, salts and glucose

Question 8

What is the basement membrane permeable to?

Answer 8

Small proteins

Question 9

What is the basement membrane made of?

Answer 9

Acellular gelatinous layer of collagen/glycoproteins

Question 10

What do podocytes form?

Answer 10

Form fenestrations/filtration slits

Question 11

A molecule under what weight and what radius can pass through the filtration barrier of the glomerulus?

Answer 11

5200 (weight)

1.48 nm

Question 12

True or false: anions are attracted to the filtration barrier so more are filtered

Answer 12

FALSE - cations are attracted because of the negatively charged glycoproteins in the basement membrane

Question 13

What happens to the filtration barrier for proteinuria to occur?

Answer 13

Negative charge is lost so proteins (anions) are readily filtered

Question 14

What makes up the net filtration pressure?

Answer 14

Hydrostatic pressure in capillary + hydrostatic pressure in Bowman’s capsule + oncotic pressure difference

Question 15

When is renal autoregulation used?

Answer 15

For acute changes, to keep renal blood flow and GFR constant

Question 16

What are the two responses of renal autoregulation?

Answer 16

Myogenic mechanism

Tubuloglomerular feedback

Question 17

Describe the myogenic response if renal BP is high

Answer 17

Constriction of afferent arteriole so less blood arrives at the glomerulus or dilate efferent arteriole (to decrease GFR)

Question 18

Describe the myogenic response if renal BP is too low

Answer 18

Dilate afferent arteriole or constrict efferent arteriole (to increase GFR)

Question 19

In which arteriole is the myogenic response more common?

Answer 19

Afferent

Question 20

What stimulates tubuloglomerular feedback?

Answer 20

Concentration of NaCl detected by NKCC2 channel on the apical membrane of macula densa (DCT)

Question 21

What does the macula densa stimulate to release different chemicals as part of the tubuloglomerular feedback mechanism?

Answer 21

Juxtaglomerular apparatus

Question 22

Describe the tubuloglomerular feedback mechanism to decrease GFR

Answer 22

Adenosine released:

• activation of A1 receptors -> constriction of afferent arteriole
• activation of A2 receptors -> dilation of efferent arteriole

Question 23

Describe the tubuloglomerular feedback mechanism to increase GFR

Answer 23

Prostaglandins released -> dilation of afferent arteriole