Exam 3: Lecture 29: Renal Blood Flow, etc. Flashcards

1
Q

About how much of overall cardiac output is received by the kidneys?

A

25%

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2
Q

If the overall renal blood flow increases what happens to the pressure gradient between renal artery and renal vein?

A

It increases

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3
Q

What is the major mechanism for changing renal blood flow?

A

Changing arteriolar resistance

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4
Q

What two mechanisms cause vasoconstriction of the renal arterioles?

A

Sympathetic nervous system and circulating catecholamines

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5
Q

If there is vasoconstriction on the -afferent arteriole, what happens to GFR?

A

It decreases

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6
Q

If there is vasoconstriction on the efferent arteriole, what happens to GFR?

A

It increases

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7
Q

Afferent/Efferent: which renal vessel has more alpha 1 receptors?

A

Afferent

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8
Q

Which renal vessel (afferent/efferent) is. more sensitive to angiotensin 2?

A

Efferent

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9
Q

T/F: Angiotensin 2 only affects efferent arterioles.

A

False - it affects both, just affects efferent more

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10
Q

Angiotensin 2 in _______ levels increases GFR.

A

Low

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11
Q

Angiotensin 2 in _________ levels decreases GFR.

A

High

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12
Q

If the RAAS system is activated, what would the result be on the GFR?

A

Decrease - the RAAS system increases the level of AG2 which causes vasoconstriction of both arterioles which decreases GFR.

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13
Q

Atrial natriuretic peptide causes _______ of afferent arterioles

A

Dilation

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14
Q

Atrial natriuretic peptide causes _______ of efferent arterioles.

A

Constriction

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15
Q

What is the overall effect on GFR from an increase in Atrial natriuretic peptide?

A

Increases

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16
Q

What two substances help to modulate vasoconstriction in the renal system in response to the sympathetic nervous system?

A
  • Prostaglandins E2 and I2
  • Dopamine
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17
Q

Renal blood flow can be maintained within what range of renal arterial pressure?

A

80-180mmHg

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18
Q

At what point would renal blood flow decrease due to renal arterial pressure?

A

When it falls below 80 mmHg

19
Q

Which renal vessel is mainly affected by low levels of angiotensin 2?

A

Efferent arteriole

20
Q

If there is an increase in renal arterial pressure, what happens to the resistance to blood flow?

A

It increases

21
Q

If both RBF and GFR increase in response to increased renal arterial pressure, how are these values brought back to normal?

A

Macula densa secretes vasoactive substances that constricts the afferent arteriole.

22
Q

How is RBF estimated?

A

Clearance of PAH

23
Q

The Fick Principle is described as what?

A

The amount of substance entering an organ equals the amount leaving

24
Q
A
25
Q

What percentage of cardiac output do the kidneys typically receive?

A

25%

26
Q

Renal plasma flow is inversely proportional to

  • Glomerular pressure
  • renal vascular resistance
  • systemic vascular resistance
  • blood viscosity
A

Renal vascular resistance

27
Q

Which arterioles are primarily involved in regulating RBF?

A

Afferent and efferent arterioles

28
Q

What is the major mechanism for altering RBF?

A

Adjusting arteriolar resistance

29
Q

Which of the following is a renal vasoconstrictior?

  • dopamine
  • ANP
  • Angiotensin II
  • Prostaglandin E2
A

Angiotensin II

30
Q

What effect do low levels of angiotensin II have on GFR

A

Increase GFR

  • due to premdominant effect on efferent arterioles
31
Q

What causes
- dilation of afferent arterioles
- constriction of efferent arterioles

A

Atrial natriuretic peptide - ANP

32
Q

What substance is responsible for dilating renal arterioles during hemorrhage

A

Dopamine

33
Q

Autoregulation of RBF maintains constant blood flow between what arterial pressures?

A

80-180mmHg

34
Q

The myogenic hypothesis of autoregulation involves:
A) The contraction of smooth muscle in response to increased arterial pressure
B) The dilation of arterioles in response to decreased blood pressure
C) The production of renin in response to reduced blood flow
D) The increased filtration rate due to high GFR

A

A

35
Q

The myogenic hypothesis of autoregulation involves:
A) The contraction of smooth muscle in response to increased arterial pressure
B) The dilation of arterioles in response to decreased blood pressure
C) The production of renin in response to reduced blood flow
D) The increased filtration rate due to high GFR

A

B

36
Q

Which of the following is used to estimate renal plasma flow (RPF)?
A) Creatinine
B) Inulin
C) Para-aminohippuric acid (PAH)
D) Urea

A

C

37
Q

What is the formula to calculate renal blood flow (RBF)?
A) RPF ÷ (1 – Hematocrit)
B) GFR ÷ RPF
C) Cardiac output ÷ Hematocrit
D) RPF ÷ GFR

A

A

38
Q

Which principle underlies the calculation of true RPF?
A) Starling’s principle
B) Fick principle
C) Bernoulli’s principle
D) Henderson-Hasselbalch principle

A

B

39
Q

To measure true RPF, you need to:
A) Sample blood from renal artery only
B) Sample blood from renal artery and vein and collect urine
C) Infuse creatinine and collect urine
D) Use an inulin infusion

A

B

40
Q

If hematocrit is 50%, what is the relationship between RBF and RPF?
A) RBF is half of RPF
B) RBF is twice RPF
C) RBF is equal to RPF
D) RBF is unrelated to RPF

A

B

41
Q

PAH is an ideal marker for measuring RPF because:
A) It is reabsorbed in the nephron
B) It is secreted into the tubule and completely removed from the blood
C) It is metabolized by the liver
D) It remains in the systemic circulation

A

B

42
Q

PAH is an ideal marker for measuring RPF because:
A) It is reabsorbed in the nephron
B) It is secreted into the tubule and completely removed from the blood
C) It is metabolized by the liver
D) It remains in the systemic circulation

A

B

43
Q

Junkk

A