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Medsci142 > Cardiovascular Physiology > Flashcards

Cardiovascular Physiology Flashcards

1
Q

What does the P wave represent on an ECG?

A

Atrial depolarisation

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2
Q

What does the T wave represent on an ECG?

A

Ventricular repolarisation

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3
Q

What does the QRS complex represent on an ECG?

A

Ventricular depolarization

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4
Q

What is a positive chronotrope?

A

Something that increases heart rate

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5
Q

What is a positive inotropy?

A

Something that increases the contractility of the heart

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6
Q

Where does nervous system regulation of the heart originate?

A

The cardiovascular centre of the medulla oblongata

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7
Q

What neurotransmitter does the vagus nerve release?

A

Acetylcholine

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8
Q

What is the effect of the PSNS on the heart?

A

Decreased heart rate

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9
Q

What is the effect of the SNS on the heart?

A

Increased heart rate

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10
Q

What is cardiac reserve?

A

The difference between the cardiac output at rest and the maximum cardiac output

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10
Q

How does hypothermia affect the heart?

A

Decreases heart rate

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11
Q

What is cardiac output?

A

The amount of blood ejected into the aorta per minute

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11
Q

How does hyperthermia affect the heart?

A

Increases heart rate

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12
Q

What is the equation for cardiac output?

A

CO = HR x SV

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13
Q

What is stroke volume?

A

The amount of blood ejected out of the ventricle each cardiac cycle

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14
Q

What is contractility?

A

The forcefulness of contraction

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14
Q

What is after-load?

A

The amount of work the heart must do to generate ventricular pressure sufficient to eject blood.

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15
Q

What is pre-load?

A

The stretch on the heart before in contracts

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16
Q

What 3 factors affect SV?

A

Preload, afterload, contractility

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17
Q

Describe the Frank-Starling law

A

The stretch of the ventricular walls as the ventricle fills determines how forceful the contraction is - the more the muscle fibres are stretched, the more forceful the contraction.

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18
Q

What is TPR?

A

The amount of force affecting resistance to blood flow throughout the circulatory system

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19
Q

Is the mean blood pressure in the aorta closer to the systolic or diastolic blood pressure?

A

Diastolic

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20
Q

What is the speed of conduction from the SA node through the Atrial muscle?

A

Slow, 0.5m/s

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20
Q

What is the speed of conduction through the AV node?

A

Very slow, 0.05m/s

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21
Q

What is the speed of conduction through the AV bundles and purkinje fibres?

A

Fast, 5m/s

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22
Q

What is the time of delay of the AP through the AV node to the ventricels?

A

100ms

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23
Q

What is the purpose of the delay in AP through the AV node?

A

Allows for the atria to contract before the ventricles to fill them with a bit more blood

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24
Q

Where is the SA node located, precisely?

A

Right atrial wall just inferior to the opening of the superior vena cava

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25
Q

Approximately how many APs does the SA node fire a minute?

A

100

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26
Q

What is the intrinsic heart rate of the SA node?

A

40-60 BPM

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26
Q

What is the size of the AP produced by the SA node (mV)

A

1.5mV

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27
Q

Where is the AV node located, precisely?

A

Interatrial septum, just anterior to the opening of the coronary sinus

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28
Q

What is the last part of the heart to contract?

A

Apex

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29
Q

What kind of junctions are between cardiac myocytes?

A

Gap

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30
Q

What causes the gradual depolarisation of pacemaker cells?

A

Leaky Na+ channels

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30
Q

Approximately how long is a pacemaker cell AP?

A

0.8 seconds

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30
Q

What ion causes depolarisation of ventricular myocytes?

A

Na+

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30
Q

What causes the plateau phase of a ventricular myocyte AP?

A

VG slow Ca2+ channels inflow and K+ outflow

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31
Q

What ion causes the repolarization of the cardiac myocytes?

A

K+

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31
Q

What is the ion that rushes into the pacemaker cells once threshold is reached?

A

Ca2+

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32
Q

What causes the repolarisation of the ventricular myocyte?

A

Ca2+ channels closing and more K+ channels opening

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33
Q

How long does a ventricular myocyte AP last?

A

300ms

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34
Q

What is the change in MP in the ventricular myocyte AP (mV)

A

-90mV to +30mV

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35
Q

What is the change in MP in the pacemaker cell AP (mV)

A

-60mV to +10mV

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36
Q

How long does the depolarisation of ventricular myocytes take?

A

1-2ms

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37
Q

How long does the plateau phase of ventricular myocyte APs last?

A

200ms

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38
Q

How long is the repolarization phase of ventricular myocyte APs?

A

20-50ms

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39
Q

What is the refractory period?

A

The time in which a second AP cannot be triggered

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40
Q

Why is it good that the cardiac refractory period last longer than the normal AP?

A

To prevent tetanus from occuring

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41
Q

Do cardiac action potentials have after-hyperpolarisation phases?

A

No

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42
Q

What is the order of waves on an ECG?

A

P, QRS, T

43
Q

What might an enlarged P wave indicate?

A

Damage/enlargement of the atria

44
Q

What does the S-T segment of an ECG represent?

A

The plateau phase of the ventricular AP, when the entire ventricle is depolarised

45
Q

When on the ECG does atrial repolarisation occur?

A

QRS wave (not seen though due to being smaller than ventricular depolarisation)

45
Q

Where are baroreceptors located?

A

Aortic arch and carotid sinus

46
Q

What is angina pectoris?

A

Pain accompanying myocardial ischemia

47
Q

What is the function of baroreceptors?

A

Monitor changes in blood pressure

48
Q

What does the vasomotor region of the cardiovascular system control?

A

Vasoconstriction

49
Q

What do cardiac accelerator nerves from the CV centre do?

A

Increase heart rate and contractility

50
Q

What are the inputs to the CV centre?

A

Proprioceptors (joint movements)

Baroreceptors (blood pressure)

Chemoreceptors (blood acidity)

Higher brain

51
Q

What are some positive inotropic agents?

A

Increased SNS

Catecholamines (e.g. NE & E)

Glucagon

Thyroid hormones

Ca2+ in extracellular fluid

52
Q

What does the cardiac accelerator nerve innervate?

A

SA node, AV node, Ventricular myocardium

53
Q

What decreases afterload?

A

Decreased arterial blood pressure

54
Q

What is starlings law of the capillaries?

A

The movement of fluid across a capillary wall depends on the balance between hydrostatic and oncotic pressure gradients

55
Q

What does and increase in venous return most directly affect?

A

Stroke volume

56
Q

What does the viscosity of blood most directly affect?

A

Vascular resistance

57
Q

What is hypertension?

A

High BP

58
Q

What is the ejection fraction calculation?

A

(EDV-ESV/EDV) x100

59
Q

How many papillary muscles are in the right ventricle?

A

3

60
Q

How many papillary muscles are in the left ventricle?

A

2

61
Q

At what region of the spinal cord do the sympathetic nerves branch off to the heart?

A

Thoracic

62
Q

Approx. how many heart beats does it take to decrease heart rate?

A

1

63
Q

Approx. how many heart beats does it take to increase heart rate?

A

5-10s

64
Q

What is tachycardia?

A

Fast resting heart rate >100bpm

64
Q

What is bradycardia?

A

Slow resting heart rate >50 bpm

65
Q

What does blood flow in specific tissue depend on?

A

Pressure differences and resistance

66
Q

What is the equation for stroke volume?

A

EDV-ESV

67
Q

What are 2 negative inotropic agents?

A

K+ & Na+

67
Q

What do positive inotropic agents usually do?

A

Increase the flow of Ca2+ into myocardium during APs to increase contraction

68
Q

What is the result of a filtration imbalance?

A

Oedema

69
Q

Where does the lymphatic system return fluid back to?

A

Jugular veins in the neck

70
Q

Every cell in the body is within ____ cells of a capillary

A

2

71
Q

What is velocity of blood proportional to?

A

1/cross sectional vessel area

72
Q

Besides arterioles alter diameter, what is another way blood flow is controlled through capillaries?

A

Pre-capillary sphincters

73
Q

What is the carotid sinus?

A

Main blood supply to the brain

74
Q

What does ANP cause?

A

Vasodilation and decreased blood volume

75
Q

What is the effect of aldosterone and ADH on blood volume?

A

Increase in blood volume

76
Q

What are some of the immediate effects of a haemorrhage?

A

Increased HR -> increase TPR (vasoconstriction) -> increased VR -> BP maintained

77
Q

What nerves connect baroreceptors to the brain?

A

Cranial nerves

78
Q

What receptors on blood vessels does the SNS stimulate?

A

Alpha receptors

78
Q

What is tonicity?

A

Vascular tone

79
Q

What is resistance proportional to?

A

1/radius

79
Q

What is the equation for BP

A

CO x TPR

80
Q

Is the circulatory structure a series or in parallel?

A

Parallel

81
Q

What is the effect of aortic plaques (atherosclerosis) on afterload?

A

Increased afterload

81
Q

What factors affect preload? (5)

A
  • Venous return
  • Blood volume
  • Filling time
  • Respiratory pump
  • Compliance (stiffness)
82
Q

What is the effect of increased afterload on SV?

A

Decreased SV

83
Q

How many baroreceptors are in the aortic arch?

A

2

84
Q

What is Poiseuille’s law?

A

Resistance is directly proportional to blood viscosity and vessel length, and inversely related to the fourth power of the radius of the blood vessel

84
Q

How many baroreceptors are in the carotid arteries?

A

2 (1 in the left, 1 in the right)

85
Q

Where are cardiopulmonary receptors located and what do the sense?

A

Located in the vena cava and sense changes in blood volume

86
Q

What 2 pressures drive filtration?

A

BHP & IFOP

87
Q

What 2 pressures drive reabsorption?

A

BCOP & IFHP

88
Q

What occurs if net filtration is positive?

A

Filtration

89
Q

What occurs if net filtration is negative?

A

Reabsorption

90
Q

What is the normal BCOP?

A

26mmHg

91
Q

What is the normal IFHP?

A

0mmHg

92
Q

What is the normal IFOP?

A

1mmHg

93
Q

Which way does IFOP flow?

A

↑
capillary

94
Q

Which way does IFHP flow?

A

↓
capillary

95
Q

Which way does BCOP flow?

A

↓
capillary

96
Q

Which way does BHP flow?

A

↑
capillary

97
Q

What is the normal BHP at the arterial end of the capillaries?

A

35mmHg

98
Q

What is the normal BHP at the venous end of the capillaries?

A

16

99
Q

What happens to fluid left in the interstitial space?

A

Gets drained by the lymphatic system

100
Q

What are the 3 methods of capillary exchange?

A

Diffusion

Transcytosis

Bulk flow/filtration

101
Q

What is transcytosis?

A

Vesicles of large lipid insoluble molecules (e.g. insulin)

102
Q

What is bulk flow/filtration?

A

Passive movement of fluid and substances

103
Q

What is the key driver of filtration?

A

Pressure gradients

104
Q

How many litres of fluid are reabsorbed by the capillaries per day?

A

17L

105
Q

How many litres of fluid are removed by the lymphatic system per day?

A

3L

106
Q

What is aortic stenosis

A

Narrowing of the aorta

107
Q

Where are the baroreceptors in the kidneys located?

A

Juxtaglomerular cells

108
Q

What is the moderator band made of?

A

Cardiac muscle

109
Q

What does the moderator band do to the papillary muscles?

A

Primes them to contract chordae tendineae ahead of ventricular contraction

Medsci142 (15 decks)

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