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CVS > 2-The Heart As A Pump > Flashcards

2-The Heart As A Pump Flashcards

1
Q

Define afterload

A

The load the heart must eject against

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2
Q

Define preload

A

Amount the ventricles are stretched during diastole

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3
Q

Define Total Peripheral Resistance (TPR)

A

The resistance to blood flow offered by all the systemic vasculature

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4
Q

Define systole

A

Phase of ventricular contraction

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5
Q

Define diastole

A

Phase of ventricular relaxation and filling

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6
Q

What is End Diastolic Volume (EDV) and when does it occur in the cardiac cycle?

A

EDV is the maximum ventricular volume and it occurs after atrial contraction

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7
Q

What is End Systolic Volume (ESV) and when in the cardiac cycle does it occur?

A

ESV is the volume of blood left in the ventricles after systole and occurs during isovolumetric relaxation

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8
Q

Define contractility

A

Contractility is the force of contraction for a given fibre length

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9
Q

What is aortic pressure equivalent to?

A

Afterload

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10
Q

What is central venous pressure equivalent to?

A

Preload

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11
Q

What is stroke volume determined by?

A

The degree of contraction during systole

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12
Q

What is EDV determined by?

A

The filling of the heart in diastole
Explanation: As ventricles fill, pressure increases as ventricle wall stretches. When ventricular pressure equals venous pressure no more filling occurs. Therefore increased venous pressure = increased ventricular filling in diastole

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13
Q

Why is internal jugular vein pressure measured?

A

As nothing impedes the flow of blood from right atrium to internal jugular vein therefore it represents right atrial pressure and right heart function.

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14
Q

What is the cardiac cycle?

A

The sequence of pressure changes and valve operations that occur with each heart beat

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15
Q

Describe the pressure changes in the internal jugular vein

A

1st- a wave caused by transient venous distension due to back pressure from right atrial contraction
2nd- v increase due to passive filling of right atrium from systemic veins during systole when tricuspid valve is closed
3rd - y decreases causes by a fall in right atrial pressure due to tricuspid valve opening in early diastole allowing rapid ejection from the right atria to right ventricle

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16
Q

What causes the 1st heart sound?

A

‘Lub’ is caused by the mitral valve closing as systolic contraction causes left ventricular pressure to exceed left atrial pressure

17
Q

What causes the 2nd heart sound?

A

‘Dub’ is caused by atrial valve closing as the left ventricular pressure decreases below aortic pressure as it relaxes

18
Q

Roughly how long does systole and diastole last?

A

Systole - 0.35 s

Diastole - 0.55 s

19
Q

Name the stages of the cardiac cycle

A
  • Atrial contraction
  • Isovolumetric contraction
  • Rapid ejection
  • Reduced ejection
  • Isovolumetric relaxation
  • Rapid filling
  • Reduced filling
20
Q

What prevents atrioventricular valves from prolapsing during systole?

A

Attachments to chordae tendinae which are attached to papillary muscles that contract in systole

21
Q

What is a valve stenosis?

A

Where the valve doesn’t open enough, so there is an obstruction when valve is normally open

22
Q

What is a valve regurgitation?

A

Where the valve doesn’t close fully, so there is back leakage when the valve should be closed.

23
Q

Where are the areas of auscultation?

A

Aortic valve - 2nd right intercostal space, sternal border
Pulmonary valve - 2nd left intercostal space, sternal border
Tricuspid valve - 4th left intercostal space, sternal border
Mitral valve - 5th left intercostal space, mid clavicular line
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24
Q

What are the causes of atrial valve stenosis?

A
  • Chronic rheumatic fever (inflammation leading to commissural fusion of leaflets)
  • Degenerative (senile calcification/fibrosis)
  • Congenital (born with bicuspid form of tricuspid valve)
25
Q

What are the consequences of atrial valve stenosis?

A
  • Stress on red blood cells leading to haemolytic anaemia
  • Increased left ventricular pressure leading to hypertrophy
  • Left sided heart failure leading to syncope/angina
26
Q

What are the causes of mitral stenosis?

A

Rheumatic fever resulting in inflammation that leads to commisural fusion of leaflets

27
Q

What are the consequences of mitral valve stenosis?

A
  • Pulmonary oedema/ dyspnea (difficultly breathing) / pulmonary hypertension, leading to right ventricular hypertrophy
  • Left atrial dilation leading to:
  • Oesophageal compression, leading to dysphagia
  • Atrial fibrillation, leading to thrombus formation
28
Q

What are the causes of mitral valve regurgitation?

A
  • Myxomatous degeneration
  • Heart attack causing damage to papillary muscles
  • Rheumatic fever
  • Left sided heart failure-> Left ventricle dilation-> valve stretched
29
Q

What are the consequences of mitral valve regurgitation?

A

Blood leaks back to left atrium, increasing preload, leading to left ventricular hypertrophy

30
Q

What are the causes of aortic valve regurgitation?

A
  • Rheumatic fever

- Aortic root dilation (aneurysm) pulling leaflets apart

31
Q

What are the consequences of aortic valve regurgitation?

A

Blood flows back to the left ventricle during diastole leading to:

  • Left ventricular hypertrophy
  • Increased stroke volume
  • Increased diastolic and systolic pressure
  • Bounding pulse
32
Q

What are the differences between the left and right sides of the heart?

A
  • Left atrial and ventricle walls thicker than right side, as it has to pump the same volume of blood further
  • Left ventricle has 2 large papillary muscles, right side has 3 smaller muscles
33
Q

What is the formula for cardiac output?

A

Cardiac output = stroke volume X heart rate

34
Q

What is the formula for stroke volume?

A

Stroke volume = EDV - ESV

35
Q

What is cardiac output determined by?

A
  • Strength of contraction

- Difficultly ejecting blood

36
Q

What changes to circulation does standing up cause?

A
  • Blood pooling in legs (due to gravity)
  • Reduced venous pressure
  • Reduced cardiac output
  • Reduced arterial pressure
  • Baroreceptor reflex and ANS increase heart rate (to compensate)
  • If baroreceptor reflex fails, hypotension and syncope*
37
Q

How is cardiac output increased in exercise?

A
  • Increased heart rate (increased sympathetic output)
  • Increased contractility (increased sympathetic output)
  • Increased venous pressure (decreased TPR)
38
Q

Explain the frank starling law

A

If you stretch fibres of the heart before contracting, it will contract harder. Therefore the more the heart fills, the harder it contracts so the greater the stroke volume

CVS (10 decks)

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