Renal Basics

Question 1

9 jobs of the kidney:

Answer 1

1. Filtration
2. blood pressure
3. Na+ homeostasis
4. K+ homeostasis
5. H2O homeastasis
6. Bone/mineral – vit D, PO4, Ca2+
7. Acid/Base
8. RBC production and regulation (EPO)
9. gluconeogenesis

Question 2

% of CO that gets first pass renal flow?

Answer 2

20%

** ~1000 mL blood per min!!!

Question 3

Normal RPF (renal plasma flow):

Answer 3

600 mL/min

or 60% of the 1000 mL total renal blood flow

**40% of blood is RBCs

Question 4

3 structure that create the barrier between glomerular capilary lumen and Bowman’s space:

Answer 4

1. capillary endothelium
2. basement membrane
3. podocytes

Question 5

What is allowed to pass through glomerlular capillary endothelium?

Answer 5

anything except protein and cells

Question 6

Aside from size, what affects passage through BM and podocyte slits?

Answer 6

charge

**negative charge make passage of negatively charged particle (ie. albumin) more difficult

Question 7

Size cutoff for freely filtered plasma components?

Answer 7

= 7,000 D

Na- 23 D

K- 39 D

urea- 60 D

Creatinine- 113 D

Question 8

Size cutoff for plasma components to be completely excluded from filtration?

Answer 8

> 70,000 D

albumin= 66,000 D (and is neg charged so normally does not filter)

Question 9

Normal glomerular capillary pressure:

Answer 9

60 mmHg

Question 10

Normal Bowman’s space pressure:

Answer 10

15 mmHg

Question 11

Normal glomerular capillary oncotic pressure:

Answer 11

29 mmHg

Question 12

Normal Bowman’s space oncotic pressure:

Answer 12

0 mmHg

Question 13

Net ultrafiltration pressure=?

Answer 13

(glomerular cap pressure + Bowman’s space oncotic pressu [both favor filtration]) - (Bowman’s space pressure + glomerular capillary oncotic pressure [both favor absorption])

Normal: (60 + 0) - (15 + 29)= 16 mmHg

Question 14

Normal GFR?

Answer 14

180 L/day

125 mL/min

Question 15

normal plasma flow in Efferent artery (ml/min)?

Answer 15

475 mL/min

600 mL (afferent) - 125 mL filtered by glomeruli

Question 16

Prostaglandins effect on glomeruli?

Answer 16

dilate afferent arteriole

Question 17

NE effect on glomeruli?

Answer 17

constrict afferent and efferent arterioles

Question 18

Angiotensin II effect on glomeruli?

Answer 18

constrict afferent and efferent arterioles

**more efferent???

Question 19

General equation for GFR:

Answer 19

GFR= excretion rate of unique solute (not reabsorbed)/(plasma conc of unique solute)

Question 20

Cockcroft-Gault equation:

Answer 20

CrCl=

[(140-age) x weight(kg) x 0.82(if female)] / [serum Cr x 72]