Session 3- GFR/Glomerulus

Question 1

Describe entire order of renal arteries and veins

Answer 1

Aorta - renal artery - segmental a - lobular a - arcuate a -interlobular a - afferent arteriole - glomerulus - efferent arteriole - peritubular capillaries - interlobular v - arcuate v- lobular v - segmental v - renal vein - IVC

Question 2

If its a juxtamedullary nephron then how is the blood route different?

Answer 2

After the efferent arteriole it goes to vasa recta and then back to interlobular v. It skips out peritubular capillaries

Question 3

What is the equivalent of peritubular capillaries in a juxtamedullary nephron

Answer 3

Vasa recta

Question 4

Does a juxtamedullary nephron have peritubular capillaries?

Answer 4

Yes, but only at the top

Question 5

What % of nephrons are cortical

Answer 5

70-80

Question 6

Differences between cortical and JXM nephron AA:EA diameter?

Answer 6

Cortical AE > EE

JXM AE = EE

Question 7

Differences between cortical and JXM nephron sympathetic innervation?

Answer 7

Cortical rich innervation, JXM poor

Question 8

Renin concentration in cortical vs JXM nephrons

Answer 8

High in cortical, 0 in JXM

Question 9

How much renal plasma flow/min?

Answer 9

605ml/min

Question 10

How much of blood coming in AA gets filtered?

Answer 10

20%

Question 11

Renal corpuscle is what?

Answer 11

glomerulus + Bowman’s capsule

Question 12

What stops proteins getting into bowman’s?

Answer 12

Basement membrane has glycoproteins with negative charge, repels negatively charged proteins
Also fenestrations and filtration slits formed by pedicels

Question 13

Why can more positively charged proteins get inside bowman’s than negative?

Answer 13

Because basement membrane has negative glycoproteins so repels them but not positive

Question 14

What is a pedicel

Answer 14

A foot process of a podocyte

Question 15

Describe the forces in and out between the glomerulus and Bowman’s

Answer 15

So small oncotic pressure out, small hydrostatic pressure out, and big hydrostatic pressure in

Question 16

Describe main ways GFR is kept constant (4)

Answer 16

1. Myogenic: if P up then AA constricts, if P down AA dilates
   Occurs more in AA than AE (but opposite in AE)
2. Tubuloglomerular feedback: macula densa cells in JGA sense NaCl conc, if low then secrete prostaglandins to dilate AA. If high secrete adenosine for A1R on AA to vasoconstrict, A2R on AE to dilate.
3. Neural- sympathetic innervation of AA and EA can vasoconstrict
4. As second line, if more stuff comes in more is reabsorbed. The same fraction is reabsorbed.

Question 17

If tubular hydrostatic pressure increased, GFR would

Answer 17

Decrease

Question 18

If glomerular oncotic pressure decreased, GFR would

Answer 18

Increase

Question 19

Bowman’s capsule oncotic pressure is…

Answer 19

Negligible (all the big proteins stay in glomerulus)

Question 20

If AA relaxed, glomerular hydrostatic P would…

Answer 20

Increase

Question 21

If both AA and EA relaxed, GFR would

Answer 21

Decrease

Question 22

In haemorrhage what decreases GFR?

Answer 22

SNS

Question 23

How does tubular glomerular feedback work?

Answer 23

Macula densa cells in the JGA detect NaCl levels to infer GFR levels
If high NaCl then release adenosine to dilate the EA and constrict the AE
If low NaCl then release PGs to dilate AE only