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HSF - Viscera > Cardiac Cycle > Flashcards

Cardiac Cycle Flashcards

1
Q

Does the pulmonary or systemic circulation have a higher pressure?

A

Systemic

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2
Q

Which structure is responsible for venous drainage of the heart?

A

Coronary sinus

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3
Q

What drains into the coronary sinus?

A

Left ventricle, most epicardial ventricular veins

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4
Q

Stages of heartbeat 1) 2) 3) 4) 5)

A

1) Late diastole 2) Arterial systole 3) Isometric ventricular contraction 4) Ventricular ejection 5) Isometric ventricular relaxation

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5
Q

What are the only part of venous and arterial vessels that run parallel in the same direction?

A

Coronary sinus, circumflex artery

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6
Q

When does left coronary flow mostly occur?

A

Diastole

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7
Q

Why does left coronary flow occur mostly during diastole?

A

Difference in pressure between aorta and left ventricle During systole there is no such difference

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8
Q

What is the rate of SA node pacemaker?

A

~70 beats/minute

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9
Q

What is the rate of AV node autorhythmicity?

A

~50 beats/minute

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10
Q

What is the rate of Purkinje fiber autorhythmicity?

A

25-40 betas/minute

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11
Q

How does the SA node communicate with the AV node?

A

Internodal pathways through the right atrium

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12
Q

Electrical conduction in heart

A

1) SA node 2) Internodal pathways 3) AV node 4) AV bundle 5) Bundle branches 6) Purkinje fibers

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13
Q

What does the ECG measure?

A

Whole heart average extracellular potential (from the body surface) Depolarisation either towards or away from electrodes

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14
Q

What are the ECG electrodes connected to in Einthoven’s triangle?

A

Left leg Right arm Left arm

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15
Q

What is isovolumetric contraction/relaxation?

A

1) Function of elastic wall of heart 2) Contraction of ventricles with no corresponding change in volume 3) When intraventricular pressure doesn’t exceed the pressure in aorta –> aortic valve doesn’t open

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16
Q

Is diastole passive?

A

No. ATP required to pump Ca from smooth muscle cytoplasm

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17
Q

How do the ventricles fill with blood?

A

25% from atrial contraction 75% passively during diastole

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18
Q

Stroke volume

A

Amount of blood injected each time the heart contracts

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19
Q

Does the nervous system regulate SA depolarisation?

A

Yes Regulated by the autonomic nervous system

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20
Q

Why do Purkinje fibers conduct AP to base of heart first?

A

So that the base of the heart contracts first This prevents blood being trapped in the heart

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21
Q

Do myocardial cells summate graded potentials?

A

No Long refractory period prevents this

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22
Q

What are the waves in an ECG?

A

1) P wave 2) QRS complex 3) T wave

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23
Q

What is the P wave?

A

Atrial depolarisation

24
Q

What is the QRS complex?

A

Ventricular depolarisation

25
Q

What do the different parts of the QRS complex represent?

A

1) Q - Depol of bundle of His, Purkinje fibers 2) R - Depol of bottom of ventricles 3) S - Depol of the upper part of ventricles

26
Q

When do the ventricles contract on an ECG?

A

In the period directly after the S wave

27
Q

When do the atria contract on an ECG?

A

In the period directly after the P wave

28
Q

What is the T wave?

A

Repolarisation of the ventricles

29
Q

What is the ST segment?

A

Depolarisation of the ventricles

30
Q

What will an ECG look like it the leads are placed 180 degrees in the opposite direction?

A

A mirror image

31
Q

Is there electrical activity elsewhere in the heart during the QRS complex?

A

Yes, but these deflections are overwhelmed by the left ventricle

32
Q

What is the standard ECG today?

A

9 electrodes, 12 leads

33
Q

How is a modern ECG represented?

A

4 lines: First 3 lines are the 12 leads (3 rows by 4 columns) Bottom line is the long arm of lead 2, which shows the rhythm of the heart

34
Q

What results in a positive ECG reading?

A

Electrical activity towards the positive electrode

35
Q

What are the three intervals of an ECG?

A

PR QRS QT

36
Q

Atrial fibrillation

A

Erratic atrial activity Not linked to SA node pacemaking Normally 1 P wave per QRS complex. This is not the case in atrial fibrillation

37
Q

Possible causes of atrial fibrillation

A

Idiopathic electrolyte imbalance Dilated atria Sympathetic hyperactivity

38
Q

Ventricular fibrillation

A

Ventricles beat independently of the atria Less common than atrial fibrillation, much more serious No obvious pattern to ECG

39
Q

Possible causes of ventricular fibrillation

A

Ischaemia in heart attack Electrocution

40
Q

How to restore normal rhythm from ventricular fibrillation

A

Defibrillator (electric shock)

41
Q

Does the diastolic pressure in the aorta fall more quickly or slowly than in the ventricles?

A

More slowly It feeds to into smaller vessels (capillaries)

42
Q

When do valves close?

A

When the pressure in the current compartment exceeds that in the previous compartment

43
Q

What can be heard and not heard from the heart?

A

Can hear turbulent flow Can’t hear laminar flow

44
Q

Heart sounds 1) 2)

A

1) Atrioventricular valves closing 2) Semilunar valves closing

45
Q

Which heart action corresponds with the sound of the atrioventricular valves closing?

A

Ventricular contraction

46
Q

Which heart action corresponds with the sound of the semilunar valves closing?

A

Ventricular relaxation

47
Q

What does a noise when the valves are open indicate?

A

A defect in the valves Non-laminar flow

48
Q

Measurements depicted on a Wigger’s diagram

A

1) ECG 2) Heart pressure 3) Heart sounds 4) Left ventricular volume

49
Q

Average time between P waves

A

~800msec

50
Q

What does the dicrotic notch represent?

A

Closure of the aortic or pulmonary valve

51
Q
A
52
Q

When does artrial systole occur relative to ECG?

A

After P wave

53
Q

When does ventricular ejection occur relative to ECG?

A

After QRS complex

54
Q

When does the left ventricle fill relative to ECG?

A

QRS complex

55
Q
A

HSF - Viscera (12 decks)

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