GFR, Blood Supply, Morphology

Question 1

Proportion blood supply to:

1. Kidneys
2. Split between cortex and medulla

Answer 1

1. 20-25% cardiac output, around 500ml/min/100g

2. 90% of this supplies cortex and 10% medulla

Question 2

How many mls/mom/100g does inner and outer medulla receive in blood supply?

Answer 2

Outer - 100

Inner - 20

Question 3

Purpose of mesangial cells?

Answer 3

1. Structural support to glomerulus
2. Can contract, thereby modifying capillary surface area available for filtration.
3. Also phagocytic, can occur outside glomerulus called Goormaghtigh cells.

Question 4

What is glomerular filtration rate estimated?

Answer 4

125mls/ min

180L/ day

Question 5

What size molecules can be filtered?

How does charge of a molecule affect filtration??

Answer 5

Molecules < 7kDa

Negative charge decreases filtration rate.

Question 6

What composition would you find in is produced by glomerular filtration?

Answer 6

A fluid similar to electrolyte composition of plasma with 30g/day of protein.

Protein is reabsorbed in proximal tubule.

Question 7

What is renal plasma blood flow?

What is filtration fraction?

Answer 7

Renal plasma flow = 600ml/ min

Therefore as GFR is 120ml/ min, filtration fraction is 20%

Question 8

How does glomerular hydrostatic pressures differ from those of other tissue capillary networks?

Answer 8

They are higher (45mmHg vs 32mmHg). This reflects that the resistance in the glomerular capillary network is from the efferent arteriolar.

Question 9

What equation describes GFR?

Answer 9

(Glomerular hydrostatic pressure + bowmans capsule oncotic pressure)

Minus

(glomerular oncotic pressure + bowman hydrostatic pressure)