Renal: Dynamics of Glomerular Filtration Flashcards Preview

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Flashcards in Renal: Dynamics of Glomerular Filtration Deck (36):
1

What does Glomerular filtrate consists of?

It's very much like blood plasma, however, it contains very little total protein. Consists mainly of inorganic ions and low-molecular-weight organic solutes in virtually the same concentrations as in the plasma.

2

What does "Freely Filtered" mean?

Substances that are present in the filtrate at the same concentration as in the plasma

3

What components of blood are freely filtered?

Ions (Na, K, CL, HCO3)
Neutral organics (glucose and Urea)
Amino acids
Peptides (insulin and ADH)

4

Volume of filtrate formed per unit time = Glomerular Filtration Rate. What is the normal GFR?

180L/day (125ml/min)

5

What is the net filtration of fluid across all other capillaries (besides the Glomerulus) in the body ?

4L/day

6

What is the average total volume of plasma in humans?

3L. ENTIRE plasma is filtered by the kidneys some 60 times a day.

7

Where is the site of Plasma Filtration?

Glomerulus

8

What determines barriers of Glomerular Filtration?

Cell Types

9

Glomerulus Cell Types:

1. Podocytes
2. Endothelial
3. Mesangial

10

What are the Glomerulus Cell Types' functions?

Podocytes: help keep things out based on size
Fenestrated Epithelium: Filter things based on size
Mesangial: modified smooth muscle cells, lay down extra-cellular matrix proteins; Keep things out based on charge

11

SUM of the Hydrostatic Pressures and the osmotic pressures resulting from protein SUBTRACTED by the oncotic or colloid osmotic pressures

Net Filtration Pressure (NFP)

12

HPglo - ( ONCOTICglo + HPbowmanspace)

NFP Equation

13

Hydrostatic pressure: Glomerulus and Bowman Space
Oncotic pressure of fluid: Glomerulus and Bowman Space

Filtration Pressures

14

What is the Filtration Rate Equation?

Rate of Filtration= Kf x NFP

15

Kf *(HydrostaticPressureGC - HydrostaticPressureBC - OncoticPressureGC)

= Kf * NFP

GFR

16

Pressure that pushes fluid out blood into capsule; FAVOR filtration

Hydrostatic Pressure

17

Pressure that pushes fluid into blood; OPPOSE filtration

Oncotic Pressure

18

What is the net outward pressure if the Afferent arteriole has 45mmHg (HPglo), -10mmHg (HPbowspace), -25mmHg (ONCOTICglo)?

If Blood Pressure drops 10mmHg of HPglo, the net outward pressure/filtration pressure equals what then?

10mmHg. 0mmHg

19

What portion of the NFP equation favors filtration?

HPglo

20

What portion of the NFP equation opposes filtration?

ONCOTICglo , HPbowspace

21

What is the relationship between Kf and GFR?

Decrease Kf, Decrease GFR

22

What can change Kf?

Glomerular disease and drugs.
Mesangial contraction, reducing area available for filtration.

23

Hydrostatic Pressure of the Glomerulus comes from what?

Blood Pressure

24

True/False: Hydrostatic Pressure of the Bowman Space is very constant

True

25

If you Dilate Afferents, is GFR increased or decreased?

Increased

26

If you Dilate Afferents and Constrict Efferents, is GFR increased or decreased?

Increased

27

What is the relationship between Hydrostatic Pressure of Bowman Space and GFR?

Decreased GFR, Increased Hydrostatic Pressure of Bowman Space

28

What is the relationship between Oncotic Pressure of Glomerulus and GFR?

Decreased Oncotic Pressure of Glomerulus, Increase GFR

29

Filtered Load

Amount of substance that is filtered per unit time and enters the nephron

30

Filtered Load Equation? (only works for freely filtered substances)

GFR*Plasma concentration

Ex: Na
125 ml/min * 140 mEq/L = 17.5 mEq/min.

31

What are the short and long-term affects from Autoregulation?

Myogenic response (short-term)
Tubuloglomerular Feedback (long-term)

32

Concentraion of glucose in plasma is 100 mg/dL and the GFR is 125 ml/min. How much glucose is filtered per min?

125 mg/min

33

A drug is noted to cause a decrease in GFR. Identify 4 possible actions of the drug that might decrease GFR.

1 Constrict glomerular mesangial cells, and decrease Kf.
2 Lower arterial pressure and hence HPglo
3 Constrict the afferent arteriole, and hence reduce HPglo
4. Dilated the efferent arteriole and reduce HPglo

34

A drug is noted to cause an increase in GFR with no change in net filtration pressure. What might the drug by doing?

It might be increasing Kf

35

If you Constrict Afferents, is GFR increased or decreased?

Decreased

36

A person is given a drug that dilates the afferent arteriole and constricts the efferent arteriole by the same amounts. Assuming no other actions of the drug, what happens to this person’s GFR and RBF?

RBF will show no change because the drug has no effect on total renal vascular resistance.
GFR will increase because of the large increase in HPglo.