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142 . Human Cardiorespiratory System > Cardiac Conduction System / ECG > Flashcards

Cardiac Conduction System / ECG Flashcards

1
Q

Describe the position of the SA node:

A

Right atrial wall near superior vena cava

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2
Q

Describe the position of the AV node:

A

The triangle of Koch, located in the Interatrial septum

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3
Q

Describe the position of the bundle of His:

A

Interventricular septum

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4
Q

Describe the position of the purkinje fibres:

A

Endocardium near apex of the heart

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5
Q

What is the function of the SA node?

A

Generates electrical impulses to begin contraction of the heart

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6
Q

Which part of the nervous system controls the rate of the SA node?

A

The autonomic nervous system

Sympathetic and Parasympathetic

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7
Q

What effect does the sympathetic nervous system have on the SA node?

A

Makes SA node generate impulses faster, speeding up heart rate

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8
Q

What is the function of the AV node?

A

Delays the signal generated by the SA node by a a fraction of a second

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9
Q

Why is the AV node important?

A

To ensure the atria are empty of blood before contraction stops

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10
Q

What effect does the parasympathetic nervous system have on the SA node?

A

Makes SA node generate impulses slower, decreasing heart rate

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11
Q

What is the function of the left His bundle branch?

A

Sends electrical signals through the Purkinje fibers to your left ventricle

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12
Q

What is the function of the His bundles?

A

To relay the impulse from the AV node to the Purkinje fibres

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13
Q

What is the function of the purkinje fibres?

A

Deliver electrical signals to the ventricles causing ventricular systole

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14
Q

What is the function of the right His bundle branch?

A

Sends electrical signals through the Purkinje fibers to your right ventricle

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15
Q

Where is the cardiovascular centre located?

A

Medulla oblongarta

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16
Q

What factors may influence the rate of SA node impulse generation?

A 
Age
Sex
Emotion
Exercise
Medication
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17
Q

What causes valves to open?

A

Pressure gradients

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18
Q

How does contraction affect the pressure in a heart chamber?

A

Contraction increases pressure

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19
Q

What causes the first heartbeat sound (S1)?

A

The closing of the atrioventricular valves

20
Q

What causes the second heartbeat sound (S2)?

A

The closing of semilunar valves

21
Q

Define cardiac output:

A

The volume of blood pumped out of each ventricle per minute

22
Q

Define stroke volume:

A

The volume of blood leaving the ventricles per contraction

23
Q

Define heart rate:

A

The number of heart beats occurring in one minute

24
Q

What is the relationship between cardiac output, stroke volume and heart rate?

A

Cardiac output = Stroke volume x Heart rate

25
Q

A stroke volume of 60ml and a heart rate of 80bpm, what would the cardiac output be?

A

4800ml

26
Q

What is ejection fraction?

A

The percentage of blood in a ventricle which is removed in a contraction

27
Q

If a ventricle is filled with 100ml of blood and 62ml leaves the aorta after contraction, what is the ejection fraction?

A

62%

28
Q

What is the end-diastolic volume (EDV)?

A

The blood in the ventricle at the end of diastole (pre-contraction)

29
Q

What is the relationship between Stroke volume, ESV and EDV?

A

Stroke volume = EDV - ESV

30
Q

What is the end-systolic volume (ESV)?

A

The blood in the ventricle at the end of systole

31
Q

An ESV of 40ml and EDV of 100ml would mean the stroke volume is what?

A

60ml

32
Q

Define preload?

A

The degree of stretch of cardiac myocytes at the end of ventricular diastole

33
Q

What is an ECG / EKG

A

A tracing of the overall electrical activity of the heart

34
Q

What are the different phases seen on an ECG?

A 
P (atrial systole)
PR segment
QRS complex (ventricular systole)
Ventricular diastole
T
35
Q

Explain what happens during phase P on an ECG:

A

The impulse causes muscle cells in the atria to depolarise and contract, resulting with atrial systole

36
Q

Explain what happens during the PR segment on an ECG:

A

The impulse reaches the AV node

37
Q

Explain what happens during the QRS complex on an ECG:

A

The impulse moves down the bundle of his to the purkinje fibres causing ventricular systole

38
Q

Explain what happens after the QRS complex on an ECG:

A

Ventricular walls start to relax and recover, this is ventricular diastole

39
Q

What is the QT Interval on an ECG?

A

The time it takes for depolarisation and repolarisation of a ventricle to occur

40
Q

What happens in phase T of an ECG?

A

Repolarisation of the ventricles

41
Q

If there is a problem with the atria which part of the ECG will change?

A

The P wave

42
Q 
The rhythmic beating of the heart is initiated by what structure?
A.    Purkinje fibres
B.    Bundle of His
C.    AV node
D.   SA node
E.    Right ventricle
A

D. SA node

43
Q 
The T wave on an ECG represents what?
A.    Ventricular depolarisation
B.    Ventricular repolarisation
C.    Atrial depolarisation
D.   Atrial repolarisation
E.    Ventricular systole
A

B. Ventricular repolarisation

44
Q

Which of the following pairs is mismatched?
A. Stroke volume is the volume of blood pumped during each heartbeat
B. Blood pressure is the force blood exerts against a blood vessel wall
C. Heart rate is the number of times the heart beats per minute
D. CO = HR x SV
E. Cardiac output is the volume of blood which passes through the heart in one heart beat

A

E. Cardiac output is the volume of blood which passes through the heart in one heart beat

45
Q

When does ventricular ejection occur?

A

When the ventricular pressure is sufficient enough to open the semilunar valves

142 . Human Cardiorespiratory System (8 decks)

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