Glomerular Filtration Flashcards Preview

Human Function- Exam 4 Material > Glomerular Filtration > Flashcards

Flashcards in Glomerular Filtration Deck (32):
1

what types of molecules are excluded from the glomerular filtration barrier?

large, negatively charged things

2

what does "perm selectivity" mean?

size and charge selective

3

what are characteristics of the glomerular capillaries?

- high hydrostatic pressure
- constant hydrostatic pressure
- large surface area for filtration

4

what is the charge of the basement membrane?

negative- repels large negative things, attracts positive things

5

what are the proteins in the filtration slit?

nephrin
podocin

6

what does nephrin do?

filtration slit protein
extracellular, linked to podocin inside foot process

7

what does podocin do?

filtration slit protein
inside foot processes, connects to nephrin and signals EC events

8

what does damage to the filtration slit do?

changes permeability

9

what is the clearance ratio formula?

Cx/Cinulin

10

why is inulin special?

inulin is freely filtered
anything larger than inulin is not filtered

11

what properties of a molecule will change its clearance ratio and how?

increased size --> decreases clearance ratio
increased positive charge--> increases clearance ratio
increased negative charge-->decreases clearance ratio a lot

12

what is serum nephritis?

increased anion filtration due to loss of negative charge at filtration barrier

13

what is the starling formula for glomerular filtration?

GFR = Kf [(Pc-Pbs) - COPx]
Kf- glomerular filtration constant (surface area and permeability)
Pc-Pbs- transmural hydrostatic pressure
COP- colloidal protein osmotic pressure

14

what is the ultrafiltration pressure equation?

Puf = (Pc - Pbs) - COPx
always positive or 0

15

how does COP change along the glomerular capillary?

increases (afferent < efferent)
water is removed, which concentrates the remaining solutes

16

how does the ultrafiltration pressure change along the length of the capillary?

decreases because COP increases

17

when is the glomerular filtration in equilibrium?

COP = hydrostatic pressure

18

what is normal GFR?

100-120ml/min (180L/day)

19

what happens at filtration equilibrium?

no reabsorption

20

what does glomerular filtration depend on?

blood flow and pressure gradient

21

how does filtration fraction vary with renal plasma flow?

normal 15-20%
low- 20%
high <15%

22

what is the effect of decreasing arteriolar resistance?

increases renal plasma flow, glomerular pressure, and GFR

23

what is the effect of increasing arteriolar resistance?

decreases RPF, glomerular pressure, and GFR

24

what controls renal blood flow?

sum of afferent and efferent resistances

25

what controls glomerular capillary pressure?

relative resistances of the afferent and efferent arterioles

26

what is the most important regulator of RPF and GFR?

afferent arteriole resistance

27

what is the effect of decreasing efferent arteriole resistance?

increases RPF
decreases glomerular capillary pressure and GFR

28

what is the effect of increasing efferent arteriole resistance?

decreases RPF
increases glomerular capillary pressure
decreases GFR with large change, increase with small

29

where does angiotension II preferentially act? what does it do?

constricts the efferent arterioles

30

what do changes in GFR affect?

Na excretion
- water excretion is affected by tubular water reabsorption

31

what are extrinsic controllers that result in decreased GFR?

sympathetic nerves- adrenergic and catacholamines
antiotension II
vasopressin (ADH)
endothelin, thromboxane
dehydration, hemorrhage

32

what are extrinsic controllers that result in increased GFR?

ANP, dopaminergic nerves, NO
prostaglandins
high dietary proteins, pregnancy