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Renal Exam 1 > (5) Renal blood flow and glomerular filtration rate (Pierce) > Flashcards

(5) Renal blood flow and glomerular filtration rate (Pierce) Flashcards

1
Q
A

Excretion rate = urine concentration * urine flow rate

60 * 0.001 = 0.06

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2
Q
A

Step 1: Identify all the variables

Step 2: Calculate clearance

Step 3: Determine GFR

B. 110 mL/min

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3
Q

What is a normal GFR?

A

Aprox 125 mL/min

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4
Q
A
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5
Q
A

A. 44.6 mL/min

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6
Q
A

A. Increase

The greater the FF, the higher the oncotic pressure in the peritubular capillaries. That is because FF represents the loss of protein free fluid into bowman’s space, thereby increasing the concentration of protein in the plasma.

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7
Q

What are these images denoting?

A

Left = PGc is the hydrostatic pressure within the glomerular capillary

Right = PBc is the hydrostatic pressure within bowman’s capsule

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8
Q

What are these forces?

A

Left= oncotic pressure within the glomerular capillary

Right = oncotic pressure within Bowman’s capsule

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9
Q

How do you calculate net filtration pressure by the glomerular capillaries?

Using these numbers

A

60-18-32 = + 10 mmHg

Being FILTERED because of the + number

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10
Q

What is the major equation for GFR?

A

Kf= ultrafiltration coefficient

Puf= Capillary ultrafiltration pressure

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11
Q

What will change our ultrafiltration coefficient (Kf)?

A

Influences to the SURFACE AREA

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12
Q

What are the major sites of regulation for hydrostatic pressures in renal vasculature?

A
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13
Q

Describe what is occuring in this image

A

Constriction/Dilation in the afferent arteriole and efferent arteriole has an effect on GFR

Constrict afferent = lower GFR

Dilate afferent = higher GFR

Constrict efferent = higher GFR

Dilate efferent = lower GFR

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14
Q

Approximate average GFR?

A

125 mL/min

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15
Q

What the things that regulate GFR?

A

Sympathetics

Vasoactive Signals

Hormones

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16
Q

What are the intrinsic mechanisms for regulating renal hemodynamics?

A

Autoregulation

Tubuloglomerular feedback

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17
Q

What are the extrinsic mechanisms for regulating renal hemodynamics?

A

Sympathetic nerves

Hormones

Composition of blood

18
Q

Where are more alpha 1 receptors located?

Afferent/efferent arteriole?

A

FAR more on the afferent arteriole

19
Q

Purpose of autoregulation?

What are the two types of reactions?

A

Maintains RBF and GFR within narrow limits across wide ranges of blood pressures

Local reflex: (myogenic)

Physiological feedback: (tubuloglomerular feedback)

20
Q

What is the autoregulatory range?

A

80-170 mmHg

21
Q

Describe what is occuring during local myogenic feedback reflex:

A

Afferent arteriolar constriction

Efferent arteriolar dilation

*When BP goes up, this reflex prevents an increase in RBF/GFR

22
Q

What transduces messages regarding the glomerulus?

What secretes renin?

What “senses”?

A

Mesangial cells

Juxtaglomerular cells

Macula densa

23
Q

What makes up the juxtaglomerular apparatus?

A
  1. Macula densa cells
  2. Juxtaglomerular (granular) cells
  3. Extraglomerular mesangial cells
24
Q

Describe what tubuloglomerular feedback is

A

Feedback mechanism between the juxtaglomerular apparatus and the tubes to modify arteriolar resistance as needed

Signals occur b/w macula densa cells and JG cells

***Maintains constant Na+ delivery to the distal tubule and constant GFR

25
Q

Describe macula densa signaling

A

When there is an increase in NaCl delivery to the macula densa…

Increase in ATP/adenosine….

Which vasoconstricts afferent arteriole via calcium signaling

Which lowers GFR

26
Q

In the case of increased renal perfusion pressure,

Signals generated by macula densa results in…

A

VASOCONSTRICTION

of afferent arteriole to decrease GFR

*Mediated by Adenosine

27
Q

In the case of decreased renal perfusion pressure,

what happens?

A

Macula densa signals to JG cells to secrete renin

Renin –> Angiotensni II (vasoconstrictor) to restore BP

Results in efferent arteriolar vasoconstriction

Macula densa causes afferent arteriolar dilation mediated by NO

28
Q

Macula densa measures

A

NaCl levels

It’s the gatekeeper

29
Q

Reduced perfusion pressure stimulates ______ secretion by the afferent arteriole

Increased perfusion pressure inhibits _______ secretion by the afferent arteriole

A

RENIN

30
Q

Sympathetic activity increases ______ secretion via Beta-adrenergic receptor stimulation

A

Renin

31
Q

When NaCl delivery to the macula densa is decreased, _______ secretion is enhanced

A

Renin

32
Q

An increase in NaCl delivery to the macula densa inhibits ______ secretion

A

Renin

33
Q

What are factors that increase sensitivity of tubuloglomerular feedback

A

Volume contraction

Adenosine

PGE

Thromboxane

Ang II

34
Q

What are factors that decrease sensitivity of tubuloglomerular feedback

A

Volume expansion

ANP

NO

cAMP

PGI

*High protein diet

35
Q
A

C. Decrease in afferent arteriolar tone

36
Q
A

D.

37
Q
A

B

38
Q
A

B. 4 fold decrease in GFR

Plasma [creatinine] is inversely proportional to GFR

39
Q
A

E. Increase in afferent arteriole tone

40
Q
A

FF = GFR/RPF

GFR = Kf*(PG-PB-πG)

=10*(70-20-35) = 150 ml/min

FF=150/428=0.35

e) 0.35

Renal Exam 1 (8 decks)

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