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Cardiovascular 2018 > Control of arterial blood pressure > Flashcards

Control of arterial blood pressure Flashcards

1
Q

Define blood pressure

A

the outwards (hydrostatic) pressure exerted by the blood on blood vessel walls

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2
Q

What is the systolic arterial blood pressure?

A

the pressure exerted by the blood on the walls of the aorta and systemic arteries when the heart contracts”: should not normally reach or exceed 140 mm Hg under resting conditions

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3
Q

What is the diastolic arterial blood pressure?

A

the pressure exerted by the blood on the walls of the aorta and systemic arteries when the heart relaxes”: should not normally reach or exceed 90 mm Hg under resting conditions

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4
Q

What is hypertension defined as?

A

Clinic blood pressure of 140/90 mmHg or higher and day time average of 135/85 mmHg or higher

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5
Q

What is pulse pressure?

A

Is the difference between systolic and diastolic blood pressures

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6
Q

What is pulse pressure normally?

A

between 30 and 50 mmHg

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7
Q

In which fashion does blood flow through arteries?

A

Laminar fashion (inaudible)

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8
Q

When does flow become turbulent?

A

if the external pressure is kept between systolic and diastolic pressure the flow become turbulent whenever blood pressure exceeds cuff pressure

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9
Q

When is the 1st Korotkoff sound heard?

A

Peak systolic pressure

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10
Q

When are the 2-3rd Korotkoff sounds heard?

A

Intermittent sounds are heard as blood pressure due to turbulent spurts of flow cyclically exceeds cuff pressure

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11
Q

When is the 4th Korotkoff sound heard?

A

The last sound is heart at minimum diastolic pressure

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12
Q

When is the 5th Korotkoff sound heard?

A

No sound is heart thereafter because of uninterrupted, smooth, laminar flow

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13
Q

When is diastolic pressure recorded

A

5th Korotkoff sound

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14
Q

What delivers the blood around the systemic circulation?

A

A Pressure Gradient
between the Aorta (AO)
and the Right Atrium (RA)

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15
Q

What is the main driving force for blood flow?

A

MAP

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16
Q

Pressure gradient=

A

Mean Arterial Pressure (MAP) – Central Venous (right atrial) Pressure (CVP)

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17
Q

What is MAP?

A

the average arterial blood pressure during a single cardiac cycle, which involves contraction and relaxation of the heart

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18
Q

How can we calculate MAP?

A 
MAP = 
[(2x diastolic pressure) + systolic pressure]/
3
or
MAP = DBP + 1/3 Pulse Pressure
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19
Q

MAP of at least –mm Hg is needed to perfuse the coronary arteries, brain, and kidneys.

A

60

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20
Q

Where are the pressure sensors in the baroreceptor reflex?

A

Baroreceptors

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21
Q

Where is the control centre in the baroreceptor reflex?

A

Medulla

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22
Q

Where are the effectors in the baroreceptor reflex?

A

Heart (HR,SV) and blood vessels (SVR)

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23
Q

How do the baroreceptor reflexes reach the medulla?

A

Through Xth cranial nerve and IXth cranial nerve

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24
Q

Explain the baroreceptor reflexes in the prevention of postural hypotension?

A

When a normal person suddenly stand-up from lying position:
The venous return to the heart decreases - effect of gravity
mean arterial pressure (MAP) very transiently decreases
This reduces the rate of firing of baroreceptors
The vagal tone to the heart decreases and the sympathetic tone to the heart increases. This increases the heart rate (HR) and stroke volume (SV)
The sympathetic constrictor tone increases. This increases the systemic vascular resistance (SVR) - arterioles are the main site for SVR
The sympathetic constrictor tone to the veins increases the venous return (VR) to the heart and stroke volume
The result is: rapid correction of the transient fall in MAP: HR INCREASES; SV INCREASES; SVR INCREASES

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25
Q

Define postural hypotension

A

Results from failure of Baroreceptor responses to gravitational shifts in blood, when moving from horizontal to vertical position

26
Q

What happens to baroreceptor firing if high BP is sustained?

A

Decreases
Baroreceptors “re-set” - they will fire again only if there is an acute change in MAP above the new higher steady state level

27
Q

What is the control of MAP in the long term?

A

Blood volume

28
Q

total body fluid=

A

intracellular fluid+extracellular fluid

29
Q

ECF volume =

A

plasma volume + interstitial fluid

30
Q

What are the two main factors affecting ECFV?

A

Water excess or deficit

Na excess or deficit

31
Q

How do hormones regulate the ECFV?

A

regulating the salt and water balance in our bodies

32
Q

Which three hormones regulate ECFV?

A

RAAS
NPs
ADH

33
Q

Where is renin released from?

A

The kidneys

34
Q

What does renin stimulate?

A

Formation of angiotensin I in the blood from angiotensinogen

35
Q

What is angiotensin I converted to and by what?

A

angiotensin II

ACE

36
Q

Where is ACE mainly produced?

A

Pulmonary vascular endothelium

37
Q

Angiotensin II stimulates the release of ———– from the ——- ——

A

aldosterone

adrenal cortex

38
Q

What does aldosterone cause?

A

Systemic vasoconstriction… increases SVR also thirst and ASH release

39
Q

aldosterone acts on the ——- to increase —— and —– retention- increasing —— ——

A

kidneys
sodium
water
plasma volume

40
Q

What mechanisms stimulate renin release from the juxtapulmonary apparatus in the kidney?

A
  1. renal artery hypotension
  2. stimulation of renal sympathetic nerves
  3. decreased NA in renal tubular fluid
41
Q

Where are peptide hormones NPs synthesised?

A

Heart, brain and other organs

42
Q

What are NPs released in response to?

A

to cardiac distension or neurohormonal stimuli

43
Q

What do NPs cause?

A

excretion of salt and water in the kidneys, thereby reducing blood volume and blood pressure

44
Q

Decreased renin release will do what to blood pressure?

A

Reduce it

45
Q

NPs act as what?

A

Vasodilators- decrease SVR

46
Q

What do NPs counteract?

A

RAAS system

47
Q

What are the two typed of natriuretic peptides released by the heart?

A

Atrial Natriuretic Peptide and Brain-type natriuretic peptide

48
Q

ANP is made of how many amino acids? Where is it stored?

A

28

Atrial myocytes

49
Q

When is ANP released?

A

in response to atrial distension (hypervolemic states)

50
Q

BNP is made of how many amino acids? Where is it synthesised?

A

32

heart ventricles and brain

51
Q

What is BNP first synthesised as?

A

prepro-BNP which is cleaved to pro-BNP and then BNP

52
Q

When is serif BNP measures?

A

Suspected Heart Failure

53
Q

Where is ADH synthesised?

A

derived from a prehormone precursor synthesised by the hypothalamus and stored in the posterior pituitary

54
Q

What stimulated ADH secretion?

A

1) reduced extracellular fluid volume or

2) increased extracellular fluid osmolality (main stimulus)

55
Q

What does plasma osmolarity indicate?

A

relative sodium-water balance

56
Q

What is plasma osmolarity monitored by?

A

Osmoreceptors mainly in the brain in close proximity to the hypothalamus

57
Q

What does ADH act upon? To do what?

A

kidney tubules

Increase reabsorption of water

58
Q

What does antidiuresis do?

A

Increase extracellular and plasma volume hence CO and BP

59
Q

what does ADH do to the blood vessels?

A

Cause vasoconstriction

Increase SVR and BP

60
Q

How is Short-term moment-to moment regulation of MAP achieved?

A

Baroreceptor reflex

Cardiovascular 2018 (39 decks)

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