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NUT1005 > Cardiovascular Physiology > Flashcards

Cardiovascular Physiology Flashcards

1
Q

What are the general functions of the cardiovascular system

A
  • Circulate gas
  • Provide cells with nutrients
  • Remove waste products of metabolism
  • stop bleeding/ clot
  • regulate body temp
  • transport hormones
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2
Q

What is diastole

A

Relaxation of heart muscle, blood enters atrium

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3
Q

What is systole

A

Heart muscle contracts, pressure in chamber increases as volume decreases to move blood

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4
Q

What is the name of the valve between the right atrium and ventricle

A

Tricuspid valve

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5
Q

What is the name of the valve between the right ventricle and pulmonary artery

A

Pulmonic valve

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6
Q

What is the name of the valve between the left atrium and ventricle

A

The mitral or bicuspid valve

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7
Q

What is the name of the valve between the left ventricle and the aorta

A

Aortic valve

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8
Q

What is the difference between the superior and inferior vena cava

A

Superior transports deoxygenated blood from upper body, infer transports deoxygenated blood from lower body to right atrium

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9
Q

What happens to vessel diameter as you move through the arterial system

A

Decreases

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10
Q

What happens to blood pressure as you move from the aorta to the vena cava

A

Decreases as blood moves down a pressure gradient

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11
Q

What happens to cross sectional area as you move through the arterial system

A

Increases as there is a greater sum of arterioles and capillaries

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12
Q

What happens to blood flow velocity as you move through the arterial system

A

Decreases as higher cross sectional area so more area for blood to flow

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13
Q

Why are arterioles resistance vessels

A

Contain circular layers of smooth muscle for vasoconstriction and vasodilation to regulate and redistribute blood flow

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14
Q

Why is the elastic tissue in the aorta important

A

Enables recoil as blood pressure decreases so constant flow is maintained as blood leaves the heart

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15
Q

How do you calculate blood pressure

A

Cardiac output x total peripheral resistance

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16
Q

What contributes to total peripheral resistance

A

Arterioles as diameter decreases

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17
Q

What is the normotensive systolic blood pressure

A

120 mmHg

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18
Q

What is normotensive diastolic blood pressure

A

80 mmHg

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19
Q

What does blood pressure measure

A

The force exerted on the walls of the vessel by the blood

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20
Q

What are the determinants of total peripheral resistance

A

Vessel diameter, vessel length and blood viscosity

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21
Q

What is the role of pre-capillary sphincters

A

Encircle capillaries at their origin and contact or relax to regulate blood flow to meet metabolic requirements

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22
Q

Why is a high cross sectional area and slow blood flow velocity beneficial in capillaries

A

Large surface area and plenty of time for exchange

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23
Q

What happens to blood flow velocity in the venous system and why

A

Increases as smaller cross sectional area than capillaries

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24
Q

Why is there a lower blood pressure in the venous system

A

Enables veins to be squeezed by contracting muscles towards the heart

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25
Q

What are cardiomyocytes

A

Cardiac muscle cells

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26
Q

What is depolarisation

A

Positively charged ions flow into the cell, causing it to become less polarised

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27
Q

What is repolarisation

A

Positively charged ions flow out of the cell, causing it to be polarised again. (greater negative charge inside)

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28
Q

At rest why can’t Na+ and Ca++ enter the cardiomyocyte

A

Membrane is impermeable to them

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29
Q

What alters the permeability of the membrane enabling Na+ and Ca++ to enter

A

Action potential reaches cell

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30
Q

What initiates muscle contraction in cardiomyocytes

A

Influx of Ca++ initiates a cascade of events to cause the interaction of actin and myosin in the myofibril and generate a force (shorten the sarcomere)

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31
Q

What initiates electrical impulses/ action potentials in cardiomyocytes

A

The Sinoatrial node (SAN)

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32
Q

Describe the SAN and it ‘s role in initiation of heart muscle contraction

A

The SAN is specialised muscle tissue in the right atrium which spontaneously depolarises and repolarises, which spreads through the RA to the AVN

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33
Q

Describe the Atrioventricular node and it’s role in muscle contraction

A

The AVN is specialised muscle tissue by the interatrial septum of the heart which receives signals from the SAN and holds onto them for a brief delay before transmitting them to the ventricles for contraction

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34
Q

What is an Electrocardiogram

A

Electrodes placed on the skin which detect voltage from electrical events of the cardiac cycle to record the electrical activity of the heart in various phases

35
Q

What are the 3 main waves of the ECG

A

P wave, QRS complex and T wave

36
Q

What does the P wag represent

A

Atrial depolarisation

37
Q

What does the QRS complex represent

A

Ventricular depolarisation and simultaneous atrial repolarisation

38
Q

What does the T wave represent

A

Ventricular repolarisation

39
Q

What are the three intervals in an ECG

A

PR, QT and TP

40
Q

What does the PR interval represent and where is it on an ECG

A

Start of P wave till start of QRS complex, represents transmission from the atria to the ventricles

41
Q

What does the QT interval represent and where is it on an ECG

A

Start of QRS to end of T wave, represents the duration between ventricular depolarisation and repolarisation

42
Q

What does the TP interval represent and where is it on an ECG

A

End of T wave to start of P wave, represents duration between ventricular repolarisation and atrial depolarisation

43
Q

What is the end diastolic volume

A

The volume of blood remaining in the left ventricle

44
Q

What is end systolic volume

A

Volume of blood left in the ventricle following stystole

45
Q

What is an isovolumetric contraction

A

Where all valves are closed so there is no change in volume in the left ventricle, while pressure rapidly increases until it exceeds aortic pressure

46
Q

What is stroke volume

A

The volume of blood ejected from the heart per beat

47
Q

How do you calculate stroke volume

A

End diastolic volume- end systolic volume

48
Q

What is an ejection fraction

A

The fraction of blood within the left ventricle ejected during systole

49
Q

How does you calculate the ejection fraction

A

Stroke volume/ end diastolic volume

50
Q

How do you calculate cardiac output

A

HR X SV

51
Q

What are the mechanisms that regulate heart rate (and therefore cardiac output)

A

Sympathetic NS, parasympathetic NS and circulating epinephrine

52
Q

How does the parasympathetic NS affect HR

A

Parasympathetic cardioinhibitory nerves innervate the SA and AV node via the vagus nerve, releasing acetylcholine to reduce depolarisation of the SA node, reducing HR and the conduction velocity (speed of spread)

53
Q

How does the sympathetic nervous system influence HR

A

Sympathetic cardioacceleror nerves innervate the SA and AV nodes, releasing norepinephrine to accelerate SA node depolarisation so the heart beats faster and conduction velocity increases

54
Q

What gland is epinephrine secreted from

A

The adrenal gland

55
Q

What mechanisms regulate stroke volume (and therefore cardiac output)

A

Sympathetic nerves and circulating epinephrine, preload and afterload

56
Q

How does the sympathetic NS influence stroke volume

A

Sympathetic nerves innervate cardiomyocytes and release norepinephrine to increase the contractile force of cardiomyocytes

57
Q

What is preload

A

The increased filling pressure in the ventricles during diastole which causes greater tension and an increased stroke volume

58
Q

What is the Frank-Starling mechanism

A

Stroke volume will increase as left ventricular volume increases (preload)

59
Q

What is Afterload

A

The resistance the left ventricle must overcome to circulate blood through the aorta

60
Q

How does afterload influence stroke volume

A

The greater the afterload, the higher the pressure that must be exceeded for blood to be ejected

61
Q

How does epinephrine influence SV

A

Released from adrenal gland and stimulates increased contractile force of cardiomyocytes

62
Q

What are neuro-hormones

A

Responses elicited by the autonomic NS which bind to the target cell or organ to cause and increase (sympathetic) or decrease (parasympathetic) in activity

63
Q

What is the neuro-hormone of the SNS

A

Norepinephrine (catecholamines)

64
Q

What is the primary neuro-hormone of the SNS

A

Acetylcholine

65
Q

What are the distribution vessels

A

Aorta, large arteries, small arteries and arterioles

66
Q

What are the resistance vessels

A

Arterioles

67
Q

What are the exchange vessels

A

Capillaries

68
Q

What are the capacitance vessels

A

Venules and veins

69
Q

What is aortic systolic pressure

A

Max pressure in aorta after ejection

70
Q

What is aortic diastolic pressure

A

Minimum pressure in aorta before ejection

71
Q

How do you calculate mean arterial pressure

A

Cardiac output x total peripheral resistance

72
Q

What variables can be altered to regulate blood pressure

A

Cardiac output and total peripheral resistance

73
Q

Why must blood flow be regulated via alterations in total peripheral resistance

A

As if all arteries dilated the heart would not be able to pump enough blood to meet metabolic demand

74
Q

What is Poiseuille’s Law

A

Flow (Q)= pressure gradient x radius of arteriole ^4/ 8x blood viscosity x vessel length

OR
Flow= pressure gradient/ resistance

75
Q

How do you calculate resistance

A

Viscosity x vessel length/ radius of vessel^4

76
Q

How does the sympathetic NS influence resistance vessel

A

Increased input = vasoconstriction
Decreased input = vasodilation

77
Q

Is the sympathetic or parasympathetic NS more involved in the regulation of vasoconstriction and dilation in resistance vessels

A

Sympathetic

78
Q

How do baroreceptors regulate blood pressure within restricted limits

A

When BP decreases there is a reduction in frequency of signals sent from baroreceptors to the cardiovascular control centre in the medulla, the control centre sends signals to the heart and blood vessels to increase cardiac output and vasoconstrict

79
Q

What are the local metabolic influences on arteriole radius and blood flow

A

Decreased oxygen pressure in blood, decreased pH, increased K+, increased CO2, increased blood lactate, increased temp

80
Q

How does nitric oxide increase blood flow

A

NO is synthesised with increased arterial stress (increased blood flow) and released by endothelial cells too reduce constriction and increase dilation

81
Q

How does the aorta dampen pulsatile pressure

A

The aorta has a high content of elastic tissue making it compliant to high blood pressure when heart contracts

82
Q

How much of total peripheral resistance is provided by resistance vessels

A

60-70%

83
Q

What are the four fundamental mechanisms responsible for cardiovascular changes during exercise

A

Mechanical, metabolic, autonomic and hormonal

84
Q

What are the receptors within muscles and how do they initiate the increase in sympathetic activity during exercise

A

Mechanoreceptors are sensitive to mechanical tension and metaboreceptors are sensitive to metabolic disturbances, during exercise they transmit signals to the cardiovascular control centre evoking alterations in sympathetic and/or parasympathetic response

NUT1005 (18 decks)

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