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2. The Heart As A Pump Flashcards

1
Q

Which vessel type are classed as ‘resistance vessels’, why is this?

A

Arteries, as they restrict blood flow to drive supply to hard to perfuse areas of the body

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2
Q

Which vessels act as capacitance vessels? How do they do this?

A

Veins

They enable the system to vary the amount of blood pumped around the body

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3
Q

Which valve is present between the right atria and right ventricle?

A

Tricuspid valve

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4
Q

Which valve is present between the left atria and ventricle?

A

Mitral valve

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5
Q

Define systole.

A

Contraction and ejection of blood from ventricles

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6
Q

Define diastole.

A

Relaxation and filling of ventricles.

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7
Q

What is stroke volume?

A

The amount of blood ejected per ventricle contraction

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8
Q

What is the average stroke volume?

A

70ml

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9
Q

What is the structure of cardiac muscle?

A

Striated
Branched
Intercalated discs between cells with gap junctions to allow action potentials to pass through myocardium easily.

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10
Q

An action potential in cardiac muscle increases the intracellular concentration of which ion?

A

Calcium

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11
Q

How does the length of the action potential in cardiomyocytes differ to others?

A

280ms

It is relatively long - lasts for the duration of a single contraction of the heart.

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12
Q

What is the function of the papillary muscles and chordae tendineae that attach to tricuspid and mitral valves?

A

Prevent inversion of the valves on systole when high pressures are exerted onto them.

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13
Q

What is the significance of atrioventricular delay?

A

Prevent the ventricles contracting at the same time as the atria, it gives them time to fill and allows atria to finish contracting.

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14
Q

How does the excitation spread through the ventricular myocardium?

A

Inner (endocardial) to outer (epicardial) surface

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15
Q

What happens to systole and diastole when heart rate increases?

A

Systole stays the same and diastole will shorten

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16
Q

Name the 7 stages of the cardiac cycle.

A
  1. Atrial Contraction
  2. Isovolumetric contraction
  3. Rapid ejection
  4. Reduced ejection
  5. Isovolumetric relaxation
  6. Rapid filling
  7. Reduced filling
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17
Q

What occurs during atrial contraction ?

A

Atria contract, accounting for the last 10-20% of ventricle filling.

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18
Q

What causes the ‘A wave’ in wiggers diagram?

A

Atrial pressures rising due to atrial systole.

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19
Q

What does the P wave on an ECG represent?

A

P wave signified the onset of atrial depolarisation.

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20
Q

What is the End-Diastolic Volume (EDV) and when is it reached?

A

It is the maximal ventricular volume, reached after atrial contraction in phase 1.

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21
Q

What is the typical EDV?

A

120ml

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22
Q

What causes the mitral valve to close during isovolumetric contraction?

A

The intraventricular pressure exceeds atrial pressure.

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23
Q

What wave is created on the atrial pressure curve when the mitral valve closes?

A

C wave

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24
Q

What does the QRS complex on an ECG signify?

A

The onset of ventricular depolarisation

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25
What causes the first heart sound, S1?
Closure of the mitral and tricuspid valves during the isovolumetric contraction phase.
26
What pressure changes cause the aortic valve to open?
During rapid ejection phase, when the intraventricular pressure exceeds the pressure within the aorta.
27
What is aortic pressure during diastole?
80mmHg
28
What it the "X descent" on the atrial pressure curve?
A decrease in the atrial pressure as the ventricle contracts and the atrial base is pulled downwards.
29
What is the "V wave" on the atrial pressure plot?
A gradual rise in atrial pressure due to continued venous return from the lungs during reduced ejection phase.
30
Which ECG wave represents ventricular repolarisation?
T-wave
31
What causes the aortic valve to close during isovolumetric relaxation in phase 5 of the cardiac cycle?
When intraventricular pressure falls below aortic pressure, there is a brief backflow of blood which causes the aortic valve to close.
32
What causes the "dicrotic notch" seen in the aortic pressure graph?
Increase in aortic pressure curve caused by the elastic recoil of the aorta following valve closure.
33
How can stroke volume be calculated?
EDV-ESV= Stroke volume
34
What is the average ESV?
80ml
35
What causes the second heart sound, S2?
Closure of the pulmonary and aortic valve.
36
When might you hear an S3 sound, what might this signify?
Sound of ventricular filling. | This is normal in children but can be a sign of pathology in adults
37
What are 2 types of abnormal valve function?
Regurgitation and Stenosis
38
What happens in stenosis of a valve?
The valve doesn't open enough, so there is obstruction to blood flow.
39
What is valve regurgitation?
The valve doesn't close all the way, so there is back leakage when the valve should be closed.
40
What are other names for valve regurgitation?
Incompetence or insufficiency
41
What are 3 causes of aortic valve stenosis?
1. Degenerative (senile calcification/fibrosis) 2. Congenital (bicuspid form of valve) 3. Chronic rheumatic fever (inflammation and fusion)
42
What is the murmur associated with aortic valve stenosis?
Crescendo-decrescendo murmur
43
How can aortic valve stenosis cause LV hypertrophy?
Less blood can get through the valve, so there is increased LV pressure, so the heart muscle hypertrophies
44
In addition to LV hypertrophy, what else can aortic valve stenosis cause?
L-sided heart failure which can lead to syncope and angina (if not enough blood supplying heart muscle) Shear stress on RBC's - microangiopathic haemolytic anaemia.
45
What are 2 causes of aortic valve regurgitation?
1. Aortic root dilation (leaflets pulled apart) | 2. Valvular damage (endocarditis rheumatic fever)
46
Which valve abnormality is associated with a bounding pulse - head bobbing and Quinke's sign?
Aortic valve regurgitation
47
What happens during aortic valve regurgitation?
Blood flows back into LV during diastole, increasing stroke volume
48
What is myxomatous mitral valve degeneration and what does it cause?
Weakening of the connective tissue which can cause valve prolapse
49
What is the consequence of mitral valve regurgitation?
As some blood leaks back into the LA when the ventricle contracts, the preload is increased as more blood enters the ventricle in subsequent cycles, leading to LV hypertrophy.
50
What is the most common cause of mitral valve stenosis?
Rheumatic fever (99.9% cases)
51
What is the consequence of mitral valve stenosis?
Harder for the blood to flow into the LV, so increased pressure in the LA.
52
What can increased pressure in the LA due to mitral valve stenosis cause?
- pulmonary oedema - dyspnea - pulmonary hypertension These all lead to RV hypertrophy (harder to pump against the higher pressures) - LA dilation which can cause atrial fibrillation and oesophagus compression and dysphagia.
53
Which valve is bicuspid?
Mitral valve
54
What happens to ventricular pressure during isovolumetric contraction?
Rapid rise in pressure as ventricle contracts and all valves are still closed.
55
What is the typical pressure in the right atrium?
0-4 mmHg
56
What is the typical pressure in the LA?
8-10 mmHg
57
What is the typical pressure in the pulmonary artery in diastole and systole?
10 diastole/ 25 systole
58
What is the typical pressure in the left ventricle in diastole and systole?
10 diastole / 120 systole
59
What is the typical pressure in the right ventricle during diastole and systole?
4 diastole/ 25 systole
60
What is the typical pressure in the aorta during diastole and systole?
80 diastole / 120 systole
61
When can aortic stenosis be heard? Explain why.
During systole, when the valve is open so the turbulent blood flow can be ausultated.
62
What happens to diastolic pressure during aortic valve regurgitation?
Decreases as blood volume is lower as some has flowed back into LV.
63
What happens to systolic pressure during aortic regurgitation?
Systolic pressure increases due to increased stroke volume - more blood in ventricles.
64
Which valve pathology is associated with a bounding pulse?
Aortic valve regurgitation
65
Aortic valve regurgitation also results in LV hypertrophy. Explain why.
Increased filling of the LV, increased systolic pressure so an increased workload.
66
Which heart structures are usually responsible for preventing mitral valve regurgitation?
Papillary muscles and chordae tendineae prevent prolapse in systole
67
Other than myxomatous degeneration, what else can cause mitral valve regurgitation?
- Damage to papillary muscle after MI - left sided HF leads to LV dilation which can stretch valve - rheumatic fever can lead to leaflet fibrosis which disrupts seal
68
Which valve pathologies result in a systolic murmur?
Aortic valve stenosis | Mitral valve regurgitation
69
Which valve pathologies result in a diastolic murmur?
Mitral valve stenosis | Aortic regurgitation
70
Explain why mitral valve stenosis can cause RV hypertrophy.
Increased pressure in the LA causes pulmonary oedema and pulmonary hypertension which increases the workload for the RV to pump the blood against.
71
What is the approx length of diastole?
0.55 seconds
72
What is the approximate length of systole?
0.35 seconds
73
One heart beat is roughly _______ seconds.
0.9 seconds
74
Where is the SA node and what is it's function?
In the RA | Pacemaker cell of the heart - generate action potential spontaneously at regular intervals.
75
What is cardiac output?
The volume of blood pumped per minute by the left ventricle. Depends on HR and SV, which both vary.
76
How might the heart sounds change during deep inspiration?
S2 can split into A2 (aortic valve closing) and P2 (pulmonary valve closing) as they are not in complete synchrony.

CVS (16 decks)

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