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Cardiac rehabilitation > Cardiac anatomy regulation of Q, exercise triggers and cardiac response to exercise > Flashcards

Cardiac anatomy regulation of Q, exercise triggers and cardiac response to exercise Flashcards

1
Q

what is stroke volume?

A

Preload - afterload

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2
Q

What is Q?

A

Cardiac output

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3
Q

What is preload?

A

the amount of blood in the ventricles before contraction (EDV)

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4
Q

what is afterload?

A

the amount of blood left in the ventricles after contraction (ESV)

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5
Q

what is the ejection fraction?

A

of the initial starting volume how much was ejected?

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6
Q

What is the equation for EF?

A

EF = SV/EDV

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7
Q

what is the equation for Q?

A

Q = HR X SV

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8
Q

approximately what is the ejection fraction at rest?

A

70%

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9
Q

what is the shortening fraction?

A

How much does the chamber reduce in size whilst it contracts

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10
Q

Approximately what is the shortening fraction at rest?

A

35%

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11
Q

How does preload affect cardiac output?

A

How well does the chamber fill prior to the hear beating?

How big is the chamber?

venous return - we want optimal venous return

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12
Q

How does afterload affect cardiac output?

A

How strong are the contractions?

How much resistance was there? A lot of resistance, more will remain in the heart

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13
Q

What factor is force directly related to regarding the hearts contractions?

A

Muscle cross-sectional area (more muscle, stronger contraction)

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14
Q

What system is adrenaline released from?

A

Sympathetic

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15
Q

What actions does the autonomic nervous system carry out and give examples?

A

Subconscious actions in the body e.g. breathing, digestion

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16
Q

What actions does the parasympathetic nervous system bring about?

A

Rest and digest

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17
Q

What system is your heart a part of?

A

Autonomic system

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18
Q

what does the parasympathetic nervous system do to heart rate?

A

Decrease it

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19
Q

The PNS is wired from the CNS to where?(3)

A

SA node
AV node
atrial muscle

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20
Q

What does the sympathetic nervous system do to heart rate?

A

increase HR

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21
Q

The SNS is wired from the CNS to where?(3)

A

SA node
AV node
ventricular muscle

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22
Q

Roughly what is a normal heart rate?

A

~72/min

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23
Q

What is a limiting factor of how much the ventricles can fill?

A

Pericardium

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24
Q

What did Stray-gundersen, Circ Res, 1986 find when they studied the hearts of dogs?

A

pericardectomy in dogs allowed a greater SV and Q and peak VO2

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25
Q

what is the frank-starling principle?

A

increase stretching of myocardial walls will increase strength of contraction

26
Q

what type of muscle does cardiac muscle have similar length-tension properties to?

A

skeletal muscle

27
Q

what is the cardiac muscle length-tension relationship?

A

increasing ventricular volume stretches the ventricular muscle towards optimum length. if we over stretch the muscle then the contractile strength starts to break away

28
Q

how does the heart muscle avoid getting to a point where contraction forces decrease

A

it becomes stiffer

29
Q

what is the typical blood volume of adults?

A

5L

30
Q

what can reduce blood volume in adults

A

haemorrhage

dehydration

31
Q

where is blood flow always maintained?

A

the brain

32
Q

how much blood resides in the veins at rest

A

two thirds

33
Q

How does the body cope with insufficient blood for maximal exercise?

A

Blood is shunted away from non-working and towards working muscles to support and sustain that exercise

34
Q

What causes resistance vessels (arterioles) smooth muscle to relax

A

vasodilators

35
Q

Give me examples of some vasodilators

A 
Increase nitric oxide
Increase bradykinin 
Increase prostaglandins 
Increase K+ 
Increase Co2
Increase lactate
Local decrease in PO2
36
Q

How does an increase in nitric oxide work as a vasodilator?

A

as we increase the blood flow through the system that will stretch the endothelium and that will stimulate the endothelium to produce nitric oxide which will further allow the vasodilation

37
Q

how do vasoconstrictors work?

A

Increase SNS activity release NE (norepinephrine) has an effect on a small amount of vasodilation (against what we are trying to achieve here).
NE acts on alpha-receptors in smooth muscle to cause constriction

38
Q

What effects are greater? Vasodilation or vasoconstriction?

A

vasodilation

39
Q

How much blood resides in the venous system at rest?

A

70%

40
Q

How do we increase venous return?

A

increase SNS activity

constriction of venous smooth muscle

venoconstriction

41
Q

How much % of blood shunting occurs through venoconstriction?

A

20%

42
Q

why do we promote blood flow back to the central circulation?

A

stop blood pooling

43
Q

what is the most important way the blood comes back

A

muscular pump

44
Q

how do we enhance various return and why ?

A

moving - veins embedded within the muscle get squeezed and result in the blood being pushed

45
Q

what happens in the heart after stole has occurred?

A

the recoil creates a low pressure environment in the ventricles actively sucking blood towards it to promote the filling

46
Q

Why does the heart twist when it beats?

A

action facilitates the wringing out of the blood

47
Q

How does breating out help push blood back towards the heart?

A

out increase in thoracic pressure then squeeze the vena cava and helps push blood back towards the heart

48
Q

How does breating in help suck blood back towards the heart?

A

♣ the pressure drops there is a low pressure in the thorax facilitate blood being sucked up back towards the heart

49
Q

what effects how much blood is left in the heart at the end of contraction?

A

volume of blood in atrial circulation

pressure in aorta at onset at onset of ejection

compliance of aorta

size of pulmonary/aorta lumen

inertial component of the ejecting blood column

systemic vascular resistance

50
Q

where does the pressure have to be lower in order to allow the blood to squirt into the valves?

A

ventricle

51
Q

what are the effects on an increased afterload?

A

increase preload

Stroke volume will be reduced in the acute phase

Reduced velocity of contraction and ejection in acute phase

Marked increase in myocardial O2 consumption

52
Q

what are mechanoreceptors?

A

movement changes

53
Q

what are metaboreceptors?

A

metabolic changes

54
Q

what are baroreceptors?

A

pressure changes

55
Q

what triggers the CV response? (3)

A

mechanoreceptors, metaboreceptors, baroreceptors

56
Q

what are metaboreceptors sensitive to?

A

Increase lactate

Increase phosphate

Increase prostaglandins

Decrease pH

57
Q

where are baroreceptors located?

A

in walls of the carotid sinus and aortic arch are baroreceptors

58
Q

where are chemoreceptors located?

A

in the walls of carotid sinus and aortic arch

59
Q

what do chemoreceptors sense?

A

high levels of CO2 in the blood

60
Q

What is the bainbridge reflex?

A

Increased cardiac filling elicits tachycardia

Increase right atrium filling from increase venous return, Stretch receptors in the right atria and vena cava stretched, Increased firing rate to brain, Brain increases SNS tone, Increase HR and SV

Cardiac rehabilitation (13 decks)

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