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Renal > 03a: Filtration and Hemodynamics > Flashcards

03a: Filtration and Hemodynamics Flashcards

1
Q

List the layers of the glomerular filtration barrier.

A
  1. Single-celled, fenestrated, cap endothelium
  2. Basement membrane (neg-charged glycoproteins)
  3. Podocytes (single-celled epithelial visceral layer of Bowman’s capsule)
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2
Q

The size/charge specificity of filtration barrier is due to (X), which cover (Y).

A 
X = neg-charged glycoproteins (nephrin)
Y = podocytes, filtration slits, and slit diaphragm
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3
Q

Filtration slit specificity: molecules larger than (X) rejected, smaller than (Y) filtered.

A 
X = 3.6 nm
Y = 1 nm
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4
Q

Filtration slit specificity: Intermediate sized molecules with (p/n) charge are better filtered.

A

Positive (cationic)

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5
Q

T/F: No albumin passes the filtration barrier in glomerulus.

A

False - small amount may filter through, but partially degraded/reabsorbed

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6
Q

T/F: Albumin normally doesn’t appear in the urine.

A

True

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7
Q

If kidneys receive 20% CO and Hct is 40%, what’s the RPF?

A

1 L/min of blood; 60% is plasma, so 600 mL/min is RPF

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8
Q

(X)% of incoming plasma is filtered at the glomerulus. If kidneys receive 20% CO, what can this tell us about GFR?

A

X = 20;
20% of RPF (which is 600 mL/min if 20% of CO);
So GFR is 120 mL/min

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9
Q

What’s the typical GFR per day? What’s the typical volume of urine excreted per day?

A

180 L/day;

only 1.8 L/day! (99% water reabsorption)

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10
Q

T/F: Ultrafiltrate has all substances present in plasma at virtually same concentration as in plasma.

A

Mostly true, EXCEPT proteins

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11
Q

Filtration coefficient is primarily a function of (X), which is increased/decreased by (Y) action of (Z) cells.

A 
X = surface area (permeability)
Y = contraction/relaxation
Z = podocytes and supporting mesangial cells
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12
Q

T/F: Glomerular capillaries have filtration coefficient that’s 100x smaller than other capillaries.

A

False - 100x larger

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13
Q

The (hydrostatic/oncotic) pressure in (glom cap/bowman’s space) is virtually zero and ignored.

A

Oncotic; bowman’s space

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14
Q

GFR is proportional to (X) pressure, which can be defined as:

A

X = ultrafiltration

[P(GC)-P(BS)]-p(GC)

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15
Q

In glomerular capillaries, what leads to (increase/decrease/constancy) of oncotic pressure as fluid moves from a to e ends?

A

Increase;

Large filtration of water and retention of proteins

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16
Q

(X) is the only site of minimal reabsorption along the glomerular capillaries.

A

NONE; no reabsorption here

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17
Q

How much (higher/lower) is hydrostatic P at efferent end of arteriole compared to afferent end? Why?

A

Virtually the same;

Low resistance to flow in the capillaries

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18
Q

Tubular reabsorption/secretion involve movement of substances across (X). Which paths can be taken?

A

X = tubular epithelium and capillaries

  1. Paracellular (between cells)
  2. Transcellular (through cell)
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19
Q

(X) fraction of Na and (Y) fraction of water filtered at glomerulus is reabsorbed at proximal tubule.

A

X = Y = 2/3

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20
Q

Most O2 consumed by kidneys is used to:

A

Energize Na transport (exit across basolateral membrane)

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21
Q

T/F: In tubules, all Na transport is active.

A

False - luminal absorption of Na is downhill process

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22
Q

Standing Osmotic Gradient Hypothesis: continuous (reabsorption/secretion) of (X) creates small (increase/decrease) of osmolality of (Y) spaces. This leads to:

A

Reabsorption;
X = Na and Cl
Increase;
Y = intercellular spaces

Drive in reabsorption of water

23
Q

The Standing Osmotic Gradient Hypothesis primarily describes (X) (reabsorption/secretion) in which part of tubules?

A

X = water
Reabsorption;
Proximal tubule

24
Q

T/F: In descending limb, the high permeability to water is due to Standing Osmotic Gradient Hypothesis.

A

False - due to high osmolality of medullary interstitium

25
Q

Glucose reabsorption in (X) tubule: its entry is carried out by Na-(dependent/independent) (Y) transporters at (luminal/basolateral) membrane.

A

X = proximal
Dependent;
Y = SGLT2 and 1
Luminal

26
Q

SGLT(1/2) is high affinity, low capacity and appears (first/second) in proximal tubule.

A

SGLT1;

second

27
Q

Glucose exits tubular cells via (X) method of transport and Na-(dependent/independent) (Y) transporters, located on (luminal/basolateral) membrane.

A

X = facilitated diffusion
Independent;
Y = GLUT2 and 1
Basolateral

28
Q

Compared to glom cap’s, peritubular cap pressure is (low/high).

A

Low

29
Q

T/F: Constriction of both aff and eff arterioles reduces RBF.

A

True (increased resistance)

30
Q

Afferent arteriole dilation (increases/decreases) hydrostatic P in glomerulus. And efferent arteriole dilation?

A

Increases;

Decreases

31
Q

T/F: Efferent arteriole constriction to any degree increases GFR.

A

False- can constrict to degree where reduced RBF compromises filtration

32
Q

T/F: Both aff and eff arterioles are innervated by sympathetic nerves.

A

True

33
Q

RBF and GFR are maintained relatively constant between arterial pressures of which range?

A

80-180 mmHg

34
Q

Myogenic response of (aff/eff) arteriole smooth muscle is mediated by (X) channels.

A

Afferent;

X = stretch-sensitive cation channels

35
Q

Angiotensin II induces preferential (increase/decrease) in (aff/eff) arteriolar resistance.

A

Increase;

Efferent

36
Q

Tubuloglomerular feedback: changes in (X) as a result of (Y) is sensed by (Z).

A 
X = tubular flow rate
Y = change in GFR
Z = macula densa cells
37
Q

Tubuloglomerular feedback: increased GFR causes vaso-(constrictor/dilator) secretion by (X) to act on (aff/eff) arterioles.

A

Vasoconstrictor;
X = macula densa
Afferent

38
Q

Tubuloglomerular feedback: it’s thought that macula densa sense change in (X), which alters (Y) of cells.

A 
X = NaCl conc in fluid delivered
Y = cell volume and/or intracell Ca levels
39
Q

Tubuloglomerular feedback: high (X) levels sensed by macula densa causes them to secrete (Y), which bind to (Z) receptors on afferent arteriolar smooth muscle.

A 
X = Na
Y = Adenosine
Z = A1 (recall that A2 receptors cause vasodilation elsewhere)
40
Q

Tubuloglomerular feedback: the mechanism’s sensitivity is modulated by (X).

A

X = status of ECF volume

41
Q

Tubuloglomerular feedback: why would sensitivity by (increased/decreased) at contracted/low ECF volume?

A

Increased;

Any spontaneous increase in GFR must be dealt with swiftly to prevent life-threatening fluid loss

42
Q

(Increase/decrease) in blood V and blood P stimulates symp nerve activation and (X) NT release. (X) interacts with (Y) receptors to cause (dilation/constriction) of (aff/eff) arterioles and (increase/reduction) of RBF/GFR.

A 
Increase;
X = NE
Y = alpha-1
Vasoconstriction;
Mainly afferent;
reduction
43
Q

Sympathetic activation of (X) receptors in (Y) cells in (aff/eff) arterioles (stimulates/inhibits) renin release.

A

X = beta-1
Y = granular
Afferent;
Stimulates

44
Q

(Increased/decreased) perfusion pressure leads to increased renin production.

A

Decreased

45
Q

(NE/renin/AII/ANP) stimulate(s) renal prostaglandin production, which has a (contract/relax) action that dampens (vasodilation/vasoconstriction) effects of (NE/renin/AII/ANP).

A

NE and AII;
relaxation;
vasoconstriction;
NE and AII

46
Q

NSAIDs can result in acute (rise/reduction) in (RBF/GFR) because of unopposed (X) due to blockage of (Y).

A

Reduction; both
X = vasoconstriction
Y = NE/AII stimulation of prostaglandin synthesis

47
Q

NO is a vasodilator produced by (X) cells and released tonically in renal circulation. (Contraction/expansion) of ECF volume stimulates its release.

A

X = endothelial and macula densa

Expansion

48
Q

Levels of dopamine (increases/decreases) with ECF volume expansion. Which effects does this have on GFR/RBF?

A

Increases;

Vasodilator leading to increase in RBF/GFR

49
Q

Levels of ANP (increases/decreases) with ECF volume expansion. Which effects does this have on GFR/RBF?

A

Increases;

Vasodilator (afferent) and vasoconstrictor (efferent) leading to increase GFR with small increase RBF

50
Q

Glumerulo-tubular balance allows increased (X) of salt and water to be compensated by their (increased/decreased) (Y). This is to avoid:

A

X = filtration
Increased;
Y = reabsorption

Avoid severe salt/water depletion

51
Q

List the two mechanisms responsible for glumerulo-tubular balance.

A
  1. Starling forces at peritubular cap’s

2. Increased delivery of organic solutes, co-transported with Na

52
Q

A near constant fraction, (X), of filtered water and salt is reabsorbed at proximal tubule.

A

X = 2/3

53
Q

At which tubule does glumerulo-tubule balance take place?

A

Proximal tubule, loop of henle, and distal tubule

Renal (8 decks)

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