Phase 1 drive cardiovascular notes- heart Flashcards

1
Q

Describe cardiac muscle

A
  1. Striated
  2. Relatively small cells
  3. Cells generally contain a single nucleus
  4. Cells joined by intercalated discs
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2
Q

What are intercalated discs?

A

Desmosomes + gap junctions

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3
Q

What is the function of desmosomes between the cardiomyocytes?

A

Holds cells together

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4
Q

What is the thick fimalment formed from?

A

Myosin

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5
Q

Describe myosin

A

Two large polypeptide heavy chains
Two light chains
Two globular heads
Long tail formed from two intertwined heavy chains

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6
Q

What are the binding sites on the myosin head for?

A

One for ATP

One for binding to actin

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7
Q

What type of enzyme does the binding site for ATP act as on the myosin head?

A

ATPase

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8
Q

What is the major component of the thin filament?

A

Actin

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9
Q

Describe the core of the thin filament?

A

Two chains of actin intertwined

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10
Q

How many binding sites are there for myosin on an actin monomer?

A

One

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11
Q

What overlies the myosin binding sites on the actin?

A

Tropomyosin

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12
Q

What does Ca2+ bind to in order for mysosin heads to be able to bind to actin?

A

Troponin

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13
Q

What causes tropomysosin the change shape, exposing the mysosin binding sites on the actin?

A

Binding of Ca2+ to troponin

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14
Q

What is the A band?

A

The region of the sarcomere that contains the myosin thick filaments

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15
Q

What is the I band?

A

The region of the sarcomere occupied by thin filaments only

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16
Q

What lines define the boundaries of a sarcomere?

A

Z lines

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17
Q

What is the H-zone?

A

Contains thick filaments only

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18
Q

Where is the M-line found?

A

In the centre of the H zone

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19
Q

What helps keep the thick filaments in the middle of each sarcomere?

A

M-line linkage Wbetween thick filaments

Titin filaments

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20
Q

How many H zones will you find in a single sarcomere?

A

1

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21
Q

How many A bands will you find in a single sarcomere?

A

1

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22
Q

Why is there a high Ca2+ concentration in the sarcoplasmic reticulum?

A

Ca2+ is actively transported into the sarcoplamsmic reticulum

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23
Q

What do the action potentials travel down in order to reach the sarcoplasmic reticulum

A

t tubules

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24
Q

Which arteries supply blood to the cardiomyocytes?

A

coronary arteries

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25
Q

Where is the origin of the coronary arteries?

A

the aorta

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26
Q

What is the vein that most of the coronary arteries drain into called?

A

the coronary sinus

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27
Q

Where does the coronary sinus empty into?

A

the right atrium

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28
Q

What connects myocardial cells that allows the spread of action potentials?

A

gap junctions

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29
Q

Where is the sinoatrial node located?

A

the right atrium (near the entrance of the superior vena cava)

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30
Q

Which node normally determines heart rate?

A

SA node

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31
Q

What are the leaky Na+ channels in nodal cells referred to?

A

funny, F-type

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32
Q

What are the two types of Ca2+ channels in nodal cells ?

A

T-type and L-type

33
Q

Rapid conduction from the SA node to the AV node occurs through which pathways?

A

Internodal pathways

34
Q

Where is the AV node located?

A

The base of the right atrium

35
Q

Why is the AV node and the bundle of His the only electrical connection between atria and ventricles?

A

Because the atria and ventricles are separated by a layer of non-conducting connective tissue

36
Q

What does the bundle of His divide into?

A

left and right bundle branches

37
Q

What are the fibres that distribute the impulse through the ventricles?

A

Purkinje fibres

38
Q

Which nerve supplies parasympathetic innervation to the heart?

A

The vagus nerve (X)

39
Q

What are the effects of parasympathetic innervation to the heart?

A
  1. Decreased heart rate
  2. Decreases force of contraction
  3. Decreases cardiac output
40
Q

What are the effects of sympathetic innervation to the heart?

A
  1. Increased heart rate
  2. Increased force of contraction
  3. Increased cardiac outout
41
Q

What does it mean if an effect is chronotropic?

A

Changes heart rate

42
Q

What does it mean if an effect is negatively chronotropic?

A

Decreases heart rate

43
Q

What does it mean if an effect is inotropic?

A

Effects force of contraction

44
Q

What does it mean if an effect is positively inotropic?

A

Increases force of contraction

45
Q

What does ECG stand for?

A

electrocardiogram

46
Q

What is an ECG a measure of?

A

currents in the extracellular fluid

47
Q

What is the p wave?

A

atrial depolarisation

48
Q

Which lead is the p wave not present in?

A

aVR

49
Q

What is the PR interval?

A

Time taken for atria to depolarise and electrical activation to get through AV node

50
Q

What is the QRS complex?

A

Ventricular depolarisation

51
Q

What is the ST segment?

A

Interval between depolarisation and repolarisation

52
Q

What is the T wave?

A

Ventricular repolarisation

53
Q

What is tachycardia?

A

Increased heart rate

54
Q

What is the word for decreased heart rate?

A

bradycardia

55
Q

What is the diagnosis when ST sgements are raised in anterior (V3-V4) and lateral (V5-V6) leads

A

acute aterolateral myocardial infarction

56
Q

What is the diagnosis when ST segments are raised in inferior leads?

A

acute inferior MI

57
Q

Why is atrial repolarisation usually not evident on an ECG?

A

Hidden by the QRS complex

58
Q

What does an impulse look like on an ECG if it is moving towards the electrode?

A

Big

59
Q

What are the standard limb leads?

A

I, II and III

60
Q

Where are the standard limb leads placed?

A

Wrists and left leg

61
Q

What does the RR interval represent?

A

Time between two QRS complexes

62
Q

What are leads V1-V6 referred to?

A

The precordial leads

63
Q

On an ECG, how long is each small square across?

A

40ms

64
Q

On an ECG, how long is each big square across?

A

0.2s

65
Q

Where are the precordial leads placed?

A

On the chest

66
Q

Apart from aVR, what does a T wave look like on a normal ECG?

A

positive

67
Q

What are the augmented leads called?

A

aVR, aVL and aVF

68
Q

How long does a typical cardiac cycle last?

A

0.8 seconds

69
Q

How long is a normal diastole?

A

0.5 seconds

70
Q

What is stroke volume?

A

Volume of blood pumped from the left ventricle per beat

71
Q

What is the cardiac output?

A

Volume of blood pumped by the heart per unit time

72
Q

What time of vasculature contributes the most to total peripheral resistance?

A

Arterioles

73
Q

What is total peripheral resistance?

A

the total resistance to flow in systemic blood vessels from the beginning of the aorta to the vena cava

74
Q

What is preload?

A

volume of blood in the left ventricle before left ventricular contraction

75
Q

How does vein dilation effect preload?

A

Dilation of veins decreases pre load as venous return is decreased

76
Q

What is afterload?

A

The pressure the left ventricle must overcome to eject blood during contraction

77
Q

What is elasticity?

A

Myocardial ability to recover after systolic stress

78
Q

What is diastolic dispensibility?

A

The pressure required to fill the ventricles to the same diastolic volume

79
Q

What is compliance?

A

How easily the heart chamber expands when filled with blood