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HSF - Viscera > Cardiac Cycle > Flashcards

Flashcards in Cardiac Cycle Deck (55):
1

Does the pulmonary or systemic circulation have a higher pressure?

Systemic

2

Which structure is responsible for venous drainage of the heart?

Coronary sinus

3

What drains into the coronary sinus?

Left ventricle, most epicardial ventricular veins

4

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

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

5

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

Coronary sinus, circumflex artery

6

When does left coronary flow mostly occur?

Diastole

7

Why does left coronary flow occur mostly during diastole?

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

8

What is the rate of SA node pacemaker?

~70 beats/minute

9

What is the rate of AV node autorhythmicity?

~50 beats/minute

10

What is the rate of Purkinje fiber autorhythmicity?

25-40 betas/minute

11

How does the SA node communicate with the AV node?

Internodal pathways through the right atrium

12

Electrical conduction in heart

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

13

What does the ECG measure?

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

14

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

Left leg Right arm Left arm

15

What is isovolumetric contraction/relaxation?

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

16

Is diastole passive?

No. ATP required to pump Ca from smooth muscle cytoplasm

17

How do the ventricles fill with blood?

25% from atrial contraction 75% passively during diastole

18

Stroke volume

Amount of blood injected each time the heart contracts

19

Does the nervous system regulate SA depolarisation?

Yes Regulated by the autonomic nervous system

20

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

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

21

Do myocardial cells summate graded potentials?

No Long refractory period prevents this

22

What are the waves in an ECG?

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

23

What is the P wave?

Atrial depolarisation

24

What is the QRS complex?

Ventricular depolarisation

25

What do the different parts of the QRS complex represent?

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

When do the ventricles contract on an ECG?

In the period directly after the S wave

27

When do the atria contract on an ECG?

In the period directly after the P wave

28

What is the T wave?

Repolarisation of the ventricles

29

What is the ST segment?

Depolarisation of the ventricles

30

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

A mirror image

31

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

Yes, but these deflections are overwhelmed by the left ventricle

32

What is the standard ECG today?

9 electrodes, 12 leads

33

How is a modern ECG represented?

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

What results in a positive ECG reading?

Electrical activity towards the positive electrode

35

What are the three intervals of an ECG?

PR QRS QT

36

Atrial fibrillation

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

Possible causes of atrial fibrillation

Idiopathic electrolyte imbalance Dilated atria Sympathetic hyperactivity

38

Ventricular fibrillation

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

39

Possible causes of ventricular fibrillation

Ischaemia in heart attack Electrocution

40

How to restore normal rhythm from ventricular fibrillation

Defibrillator (electric shock)

41

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

More slowly It feeds to into smaller vessels (capillaries)

42

When do valves close?

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

43

What can be heard and not heard from the heart?

Can hear turbulent flow Can't hear laminar flow

44

Heart sounds 1) 2)

1) Atrioventricular valves closing 2) Semilunar valves closing

45

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

Ventricular contraction

46

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

Ventricular relaxation

47

What does a noise when the valves are open indicate?

A defect in the valves Non-laminar flow

48

Measurements depicted on a Wigger's diagram

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

49

Average time between P waves

~800msec

50

What does the dicrotic notch represent?

Closure of the aortic or pulmonary valve

51

Q image thumb

A image thumb
52

When does artrial systole occur relative to ECG?

After P wave

53

When does ventricular ejection occur relative to ECG?

After QRS complex

54

When does the left ventricle fill relative to ECG?

QRS complex

55