Control Arterial pressure - long term Flashcards

1
Q

Why can’t baroreceptors provide information about absolute blood pressure?

A

Relationship between pressure and baroreceptor action potential firing frequency is not fixed

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2
Q

What does resetting the baroreflex allow?

A

High cardiac output to be maintained without a fall in heart rate due to systolic pressure

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3
Q

What does hypertensive cause?

A

Sensitivity of baroreceptors is reduced

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4
Q

What is the major role of the baroreflex?

A

Buffer short-term fluctuations

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5
Q

How is blood pressure regulated in the long term?

A

Maintenance of a normal extracellular fluid volume

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6
Q

How is ECF volume regulated?

A

Renal excretion of salt and water

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7
Q

What happens if blood volume decreases?

A

MAP decreases

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8
Q

What do cardiovascular mechanoreceptors control?

A

Angiotensin II
Aldosterone
Vasopressin
Natriuretic peptides

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9
Q

What does the JGA comprise of?

A

Juxtaglomerular cells, mesangial cells and macula densa

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10
Q

What is the role of the macula densa cells?

A

Detect sodium levels
secrete vasoactive agents that affect afferent arterioles

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11
Q

What is the role of the juxtaglomerular cells?

A

Sense renal pressure changes - stretch receptors
Increases renin secretion
Depend on paracrine signalling from macula densa

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12
Q

What receptors act on the juxtaglomerular cells of afferent arterioles?

A

beta 1 adrenoreceptors

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13
Q

What factors stimulate renin release?

A

Low blood pressure
Increased sympathetic activity

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14
Q

What is the enzyme that converts angiotensin 1 to angiotensin 2?

A

ACE - angiotensin converting enzyme

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15
Q

What is the role of angiotensin II?

A

Increase blood pressure (MAP)
Stimulates sympathetic vasoconstriction
Increases thirst - increases secretion of vasopressin

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16
Q

When is renal sympathetic nerve activity (RSNA) increased?

A

Arterial baroreceptors detect a fall in arterial pressure
Veno-arterial mechanoreceptors detect a fall in central blood volume

17
Q

What does increased RSNA cause?

A

Increases renin secretion
Salt and water retention by kidneys

18
Q

What does increased RSNA stimulate?

A

Afferent arteriole constriction
Reduced GFR
Adrenaline release from adrenal medulla - renin release

19
Q

What does renin release cause?

A

Noradrenaline release
Granular cells secretion
Vasoconstriction of afferent arterioles
Lower GFR
Macula densa cell secretion

20
Q

What does aldosterone stimulate?

A

Increases Na+ reabsorption in collecting ducts and distal tubule

21
Q

What does ADH stimulate?

A

Water retention by the kidneys

22
Q

What is ADH secretion enhanced by?

A

Angiotensin II
Reduced central blood volume and arterial pressure

23
Q

What are natriuretic peptides produced by?

A

Some atrial and ventricular myocytes in response to increased blood volume

24
Q

What do natriuretic peptides stimulate?

A

Na+ excretion
Vasodilation

25
What are two types of natriuretic peptides?
Atrial natriuretic peptide (ANP) Brain natriuretic peptide (BNP)
26
How do natriuretic peptides enhance renal salt and water excretion?
Afferent arteriole dilation inhibition of Na+ reabsorption inhibition of renin and aldosterone secretion
27
What happens in renal artery stenosis?
Blood supply decreased Blood flow is decreased less oxygen due to atherosclerosis
28
What does renal artery stenosis cause?
Renin secretion -> hypotension