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PHYSL 404 - Cardiovascular Physiology > 11 Regulation of BP > Flashcards

11 Regulation of BP Flashcards

1
Q

How to calculate Cardiac output? (2)

A

Cardiac output = Stroke volume x heart rate
CO = arterial pressure/peripheral resistance

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2
Q

How will an expanded volume lead to an increase in blood pressure?

A

Volume expansion → ↑venous return → ↑cardiac output → over perfusion of tissues → Autoregulatory vasoconstriction → ↑peripheral resistance → ↑BP

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3
Q

________ is increased in advanced renal failure

A

ECVF (extracellular fluid volume) is increased in advanced renal failure

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4
Q

ECVF and ______ intake/output are related

A

ECVF and sodium intake/output are related

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5
Q

↑blood volume → ↑ BP → triggers: (fast/slow responses)

A
  • Fast response:
    • Compensation by cardiovascular system
    • Vasodilation | ↓Cardiac output
      • ↓BP
  • Slow response:
    • Compensation by kidneys
      • Excretion of fluid in urine; ↓Blood volume
        • ↓BP
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6
Q

What senses BP?

A
  • Carotid and Aortic Baroreceptors → Medullary CV center
    • Medullary CV control centre → parasympathetic neurons → SA node
    • Medullary CV control centre → Sympathetic neurons → SA node; Ventricles; veins; arterioles
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7
Q

Fill in the chart of what happens after mean arterial bp decreases upon standing

A

↓mean arterial BP → ↓firing of carotid and aortic baroreceptors → Cardiovascular control center in medulla →

  • → 1) ⇡sympathetic output →
    • Arterioles and veins → vasoconstrict → ↑peripheral resistance → ↑BP
    • Ventricles → ↑force of contraction → increase cardiac output → increase BP
    • SA node → ↑heart rate → increase cardiac output → increase BP
    • →2) decrease parasympathetic output → SA node → increased hr → increase CO → increased BP
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8
Q

How is bp controlled by RAS. Use Hypotension as an example

A
  • Hypotension
    • 1) →↓ Renal perfusion
      • a) ↓afferent arteriolar pressure
      • b) ↓delivery to macula densa
    • 2) ↑sympathetic nerve activity
    • All leads to ↑Renin Release
    • ↑renin release → Systemic vasoconstriction; aldosterone release ; sodium reabsorption; decrease in RBF and GFR
    • → Restoration of BP
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9
Q

What is the function of enalapril?

A

Enalapril blocks angiotension II to reduce hypertension

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10
Q

What is the central role of the kidney in BP regulation?

A

Renal salt handling

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11
Q

Which cells of the nephron have the highest number of mitochondria? Why?

A

Proximal Convoluted tubule has lots of mito because it requires lots of energy for reabsorption

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12
Q

Kidney’s role in bp regulation

100% plasma volume enters through the _______

20% of volume is filtered through the _______ in the ______ and enters the _____

>19% of filtered fluid is reabsorbed by the ________

<1% of volume is ________

A

Kidney’s role in bp regulation

100% plasma volume enters through the afferent arteriole

20% of volume is filtered through the glomerulus in the bowman’s capsule and enters the proximal convoluted tubule

>19% of filtered fluid is reabsorbed by the proximal convoluted tubule

<1% of volume is excreted to external environment

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13
Q

How much glomerular filtrate is reabsorbed in each portion of the nephron:

Proximal tubule:

Loop of Henle:

Distal Tubule/Collecting Duct:

A

How much glomerular filtrate is reabsorbed in each portion of the nephron:

Proximal tubule: 70%

Loop of Henle: 25%

Distal Tubule/Collecting Duct: 4%

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14
Q

What is glomerulotubular balance (GTB)

A

The ability of each successive segment of the proximal tubule to reabsorb a constant fraction of glomerular filtrate and solutes delivered to it (Fixed fraction)

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15
Q

What is pressure natriuresis?

A

The approximately linear relationship between the rate of urinary sodium excretion UNaV and the systemic mean arterial pressure

increase BP → increase volume urine

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16
Q

What is a renal function curve?

A

Shows the relationship between arterial pressure and urine output

Glomerulotubular balance (GTB) and Pressure natriuresis

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17
Q

What happens to urinary volume output as arterial pressure increases>

A

Urine volume output increases

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18
Q

How does salt consumption alter bp?

A

At increased Na+ consumption, the renal function curve is steeper - bp is elevated to make up for increased Na+

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19
Q

What happens if you clamp the renal arteries to prevent changes in BP?

A

W/o the change, kidneys become hypertensive → because they can’t remove excess Na+

20
Q

Renin coverts ________ into ________

A

Renin coverts angiotensinogen into angiotensin I

21
Q

What converts angiotensin I into Ang II

A

Angiotensin converting enzyme (ACE)

22
Q

What is the relationship between RAS and covid?

A

Inflammation from covid from spike protein binding to ANGII

23
Q

Most hemodynamic (_____) actions of AngII are mediated via the ______ receptor

A

Most hemodynamic (vasoconstrictor) actions of AngII are mediated via the _AT1`_receptor

24
Q

The sodium retaining actions of Ang II are mediated via the _____ receptor

A

The sodium retaining actions of Ang II are mediated via the AT1 receptor

25
Q

The AT2 receptor has some ill-defined _______ properties

A

The AT2 receptor has some ill-defined The AT2 receptor has some ill-defined _______ properties vasodilator properties

26
Q

Which three organs/systems have a complete renin-angiotensin system?

A
  • Kidney (in particular the proximal tubule)
  • Vasculature
  • Heart
27
Q

The local renin angiotensin systems are capable of producing high levels of _____

A

The local renin angiotensin systems are capable of producing high levels of Ang II (inflammation)

28
Q

Why is angiotensin more influential than aldosterone?

A

Ang II is very potent and overrides pressure changes

Ang II directly regulates Na+ excretion

29
Q

Why does Ang I have to be converted to Ang II?

A

Ang I is not biologically active

30
Q

Ang II is involved in ______ and ________

A

Ang II is involved in inflammation and vascular damage

31
Q

What is aldosterone?

A

Steroid hormone from adrenal cortex that stimulates Na+ uptake and K+ secretion

Increases channel synthesis

Greatest stimulation is increased [K+]

32
Q

5 steps to aldosterone function:

A
  1. Aldosterone combines with a cytoplasmic receptor (mineralocorticoid receptor)
  2. Hormone-receptor complex initiates transcription in the nucleus
  3. New protein channels and pumps are made
  4. Aldosterone-induced proteins modify existing proteins
  5. Result is increased Na+ reabsorption and K+ secretion
33
Q

tubuloglomerular feedback system

What is the function of the macula densa cells?

A

These cells are in close approximation to the juxtaglomerular vascular smooth muscle cells of the afferent arterioles of their glomeruli, and together they form what is known as the juxtaglomerular apparatus

Sense distal tubule flow and release paracrines that affect afferent arteriole diameter

34
Q

How does the tubuloglomerular feedback system help regulate sodium excretion?

A
35
Q

Explain what is happening at 1-5 in the image of tubuloglomerular feedback starting with increase GFR and then what happens after to reduce GFR

A
  1. ↑GFR
  2. ↑ Flow through tubule
  3. ↑ flow past macula densa
  4. Paracrine from macula densa to afferent arteriole
  5. Afferent arteriole constricts
  6. ↑Resistance in afferent arteriole
  7. ↓Hydrostatic pressure in glomerulus
  8. ↓GFR
36
Q

In addition to tubuloglomerular feedback, what other mechanism works to regulate Na+ excretion

A

Myogenic response

37
Q

How does increase BP affect renal blood flow?

A

Because the tubuloglomerular feedback system stabilizes Na+ excretion there is no change in Renal blood flow

38
Q

Low sodium delivery to the kidney is sensed by the ______ to cause: (slow and fast responses)

A

Low sodium delivery to the kidney is sensed by the Macula densa to cause:

  • TGF deactivation (instantaneous)
  • Renin release (slower response)
39
Q

Normal BP:

Systolic:

Diastolic:

A

Normal BP:

Systolic: <120mmHg

Diastolic: <80mmHg

40
Q

Prehypertension

Systolic:

Diastolic:

A

Prehypertension

Systolic: 120-139

Diastolic: 80-89

41
Q

Hypertension:

Stage 1)

Systolic

Diastolic

A

Hypertension:

Stage 1)

Systolic: 140-159

Diastolic: 90-99

42
Q

Hypertension

Stage 2

Systolic:

Diastolic:

A

Hypertension

Stage 2

Systolic: >/= 160

Diastolic: >/= 100

43
Q

When there is no known cause of hypertension it is known as:

A

Primary hypertension (or essential hypertension)

44
Q

When there is a known cause of hypertension it is known as:

A

Secondary Hypertension

45
Q

What are three causes of hypertension?

A

Renal hypertension (kidney failure)

Renovascular hypertension

Endocrine hypertension

46
Q

Deficits in which 5 substances can cause hypertension?

A
  • Nitric oxide
  • ANP (atrial natriuretic peptide)
  • BNP (Brain natriuretic peptide)
  • CNP (C-type natriuretic peptide)
  • Vasodilator prostaglandins etc etc

Work on Vasculature and kidney (Na+ reabsorbs)

47
Q

Excess of ______, _______ etc etc causes hypertension

A

Excess of Endothelin, Thromboxane etc etc causes hypertension

PHYSL 404 - Cardiovascular Physiology (17 decks)

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