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Renal-1 > Glomerular Filtration and Renal Blood Flow > Flashcards

Glomerular Filtration and Renal Blood Flow Flashcards

1
Q

How does a high protein diet affect TGF?

A

enhances NaCl resorption before macula densa –> increased renin –> if persists for a long time, can desensitise TGF

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2
Q

What occurs if you constrict the afferent arteriole?

A

Puf and GFR decrease

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3
Q

What is creatinine useful for?

A

long-term monitoring of kindy function

freely filtered at the glomerulus, but a small amount is also secreted = not ideal marker, but easy to measure clinically

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4
Q

When does GFR = Clearance rate?

A
  1. substance must be freely filterable in the glomeruli
  2. substance must be neither reabsorbed nor secreted by tubules
  3. must not be made, broken down, or accumulated by the kidney
  4. must be physiologically inert (not toxic, doesn’t affect renal fxn)
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5
Q

What happens when there is decreased perfusion pressure?

A

macula densa –> JG –> secrete renin –> Angiotensin II –> efferent arteriolar vasoconstriction

also results in afferent dilation through NO

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6
Q

How does tubuloglomerular feedback work?

A

macula densa cells sense NaCl –> send signal to juxtaglomerular/granular cells to produce renin –> can also signal mesangial cells to contract

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7
Q

What is nephrin?

A

one of the proteins found in the filtration slit diaphragm

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8
Q

What is the effect of sympathetic stimulation on the kidneys?

A

constrict arterioles –> decrease RBF/GFR

activate alpha-1 receptors on afferent arterioles

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9
Q

How does the macula densa signaling work if there is too much NaCl?

A

NaCl will activate NKCC transporter a lot –> increased ATP/adenosine –> thru calcium signaling, will vasoconstrict afferent arterioles –> decreased GFR –> less salt coming in

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10
Q

What receptor is on tubular epithelial cells that, when stimulated, increases Na resorption?

A

alpha-1

note: acts on Na-K ATPase

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11
Q

How do Puf and πgc change from afferent to efferent arterioles?

A

πgc increases and Puf decreases

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12
Q

What arterioles does antiotensin preferentially act on?

A

efferent arterioles

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13
Q

What receptor is used for renin release?

A

beta-1 adrenoceptor

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14
Q

How does vascular hydrostatic pressure change from the renal artery to peritubular capillary?

A

high in renal A

decreases a lot across afferent a

stays relatively high in glomerular capillary

decreases a lot across efferent a

low in peritubular c

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15
Q

What happens if there is increased renal perfussion pressure?

A

macula densa signaled –> adenosine –> vasoconstriction of afferent arteriole

(similar to when it senses too much NaCl)

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16
Q

What are the intrinsic renal hemodynamics control mechanisms?

A

autoregulation

tubuloglomerular feedback

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17
Q

What are the 3 physical factors contributing to GFR?

A

hydraulic conductivity = permeability/porosity of the fenestrated endothelium

surface area for filtration

capillary ultrafiltration pressure

18
Q

What is the autoregulatory range?

What happens outside this range?

A

10-170 mmHg is the range at which autoregulatory mechanisms are effective to maintain stable renal blood flow

below range –> blood flow will still decrease

above range –> blood flow will still increase

19
Q

What is PAH used for?

A

estimates renal plasma flow

freely filtered and also secreted –> amount of PAH in plasma of renal arter is abt equal to the amount excreted in urine

must be administered by continuous IV fusion

20
Q

What is the main thing altering Puf?

A

changing glomerular capillary pressure (Pgc)

21
Q

What cells release renin?

A

granular cells

22
Q

What does glomerulartubular balance do?

A

higher GFR –> more plasma water filtered –> higher oncotic pressure in efferent arteriole

increased GFR –> more water and sodium reabsorbed back into arterioles

23
Q

If RBF decreases due to hemorrhage, what must happen to maintain normal FF?

A

GFR must increase

FF = GFR/RBF

24
Q

What happens if you damage the filtration barrier so that the negative charges on the barrier are removed?

A

increased filtration of anions

25
Q

How are plasma creatinine levels and GFR related?

A

inversely proportional

(the more creatinine still in the blood, the less is being filtered)

26
Q

What is the filtration slit diaphragm?

A

complex of molecular barriers btw podocyte arms that acts to filter molecules as they pass through the filtration slit

27
Q

What happens if you constrict the efferent arteriole?

A

GFR and Puf increase

28
Q

What does a low BUN:Cr ratio indicate?

A

intrarenal problem

renal diseases reduce BUN reabsorption therefore decreasing plasma levels

29
Q

What are the 3 layers of the glomerular filtration barrier?

A

capillary endothelium = fenestrae glomerular

basement membrane

podocyte epithelium = filtration slits

30
Q

What does a high BUN/Cr ratio indicate?

A

>20:1

pre-renal problem

BUN reabsorption is increased

31
Q

What receptor is used to constrict afferent arterioles?

A

alpha-1 receptors

32
Q

What are the 2 main substances listed that follow the GFR = Cx rule?

A

inulin

creatinine (not perfect though)

33
Q

As filtration fraction increases, what happens to the oncotic pressure of efferent arteriole?

A

oncotic pressure increases bc more fluid is pulled out of blood therefore it is more concentrated

34
Q

What are the extrinsic control mechanisms of renal hemodynamics?

A

sympathetic nerves

hormones

composition of blood

35
Q

What is the biogel made of and where is it located?

A

on capillary endothelium

made of glycocalyx = hyaluronan, and heparan sulfate

biogel = negatively charged, so other negatively charged molecules are repelled

36
Q

What is the myogenic reflex?

A

increased pressure in blood vessels –> local reflex btw vascular smooth muscle cells –> afferent constriction and efferent dilation via calcium signaling

37
Q

What is the estimated normal filtration fraction?

A

~20% = GFR/RBF

38
Q

What are the relative filterabilities of neutral, anionic, and cationic molecules?

A

anionic = least filterable

neutral = middle

cationic = most filterable

39
Q

What is special about inulin?

A

amount excreted in urine = amount filtered

GFR = Cx

Bc inulin isn’t reabsorbed or secreted

40
Q

What size molecules are freely filtered?

What size molecules are not filtered at all?

A

< 20 A = Free

> 42 A = not filtered

41
Q

What is a normal BUN:Cr ratio?

A

10-20:1

42
Q

Where are there more alpha-1 receptors?

A

on afferent arteriole

(more than efferent - bc want to decrease filtration if you are fighting/flighting)

Renal-1 (14 decks)

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