Renal Blood Flow and Glomerular Filtration - Rao Flashcards Preview

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Flashcards in Renal Blood Flow and Glomerular Filtration - Rao Deck (30):
1

What two vascular structures have the highest resistance in the nephron? What is a distant third?

Efferent Arteriole > Afferent Arteriole > Peritubular Capillary

2

What is the Gibbs Donnan effect?

4-5% more anions than cations present in filtrate because cations can bind negatively charged proteins in plasma

3

What is the equation for filtration fraction?

FF = GFR / RPF

4

Name one factor that can reduce GFR and one that can reduce RPF?

GFR - urethral obstruction
RPF - renal artery stenosis

5

What are the three filtration barriers in the glomerulus?

Capillary Endothelium
Basement Membrane
Epithelium (Podocyte monolayer)

6

What is an equation for GFR?

GFR = Kf x Net filtration pressure

7

What is Kf?

Filtration coefficient = hydraulic conductivity x surface area of glomerular capillary

8

What is the equation for net filtration pressure?

(P g + Pi bs) - (Pi g + P bs)
g -glomerulus
bs - bowman's space
P - hydrostatic
Pi - oncotic

9

How does increased afferent or decreased efferent arteriole pressure effect GFR?

Decreases GFR

10

How does decreased afferent or increased efferent arteriole pressure effect GFR?

Increases GFR

11

How does increased afferent arteriole pressure affect GFR and RPF, respectively?

GFR - decrease
RPF - decrease

12

How does decreased afferent arteriole pressure affect GFR and RPF, respectively?

GFR - increase
RPF - increase

13

How does increased efferent arteriole pressure affect GFR and RPF, respectively?

GFR - increase
RPF - decrease

14

How does decreased efferent arteriole pressure affect GFR and RPF, respectively?

GFR - decrease
RPF - increase

15

How does increased hydrostatic pressure in bowman's space affect GFR?

Decreases GFR (through decreased net filtration rate)

16

How does low capillary flow affect GFR?

Low capillary flow - Increased filtration fraction - Increased glomerular oncotic pressure - Decrease net filtration pressure - Decrease GFR

17

How do GFR and RPF remain constant through a range of mean arterial pressures?

Change renal vascular resistance (particularly afferent arteriole)

18

What is the mycogenic mechanism?

Major theory of GFR auto-regulation
Direct simulation of arteriolar smooth muscle

19

What is the tubuloglomerular feedback mechanism?

Major theory of GFR auto-regulation
Juxtaglomerular apparatus (macula densa cells and juxtaglomerular cells)
Stimulated by GFR and tubular chloride
High flow / chloride causes decreased GFR

20

How does high chloride in macula densa decrease GFR?

High chloride stimulates NA-K-2Cl cotransporter in JG cells
JG cells release ATP and AA metabolites
Smooth muscle contraction
Increase arteriolar resistance

21

What activates the Renin Angiotensin System?

Decreased arterial pressure
Decreased ECF volume

22

List the cascade of events from stimulation to effect of the RAS.

Decreased arterial pressure / ECF volume
Decreased glomerular hydrostatic pressure / GFR
Decreased chloride at macula densa
Renin secretion from juxtaglomerular cells
Increased angiotensin I
Increased angiotensin II (constricts arterioles and decreases GFR)
Aldosterone
Na and water retention

23

How does sympathetic activation affect GFR?

Constrict afferent arterioles and decrease GFR

24

How does adrenaline affect GFR?

Constrict arterioles (preferentially afferent) and decrease GFR

25

How does Endothelin-1 affect GFR?

Constrict arterioles (afferent and efferent) and decrease GFR

26

How does NO affect GFR?

Decrease vascular resistance and increase GFR

27

How do prostaglandins affect GFR?

Decrease vascular resistance and increase GFR

28

What is visible barrier breakdown and what is present in the urine?

Increased glomerular pore size
Protein (albumin) and cells

29

What is invisible barrier breakdown and what is present in the urine?

Loss of charge selectivity
Protein (albumin)

30

Define nephritic vs. nephrotic.

Nephritic - visible barrier breakdown; protein + cells in urine
Nephrotic - invisible barrier breakdown; protein in urine