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ESA 2 SEMESTER 2 TK > CVS - The Heart As A Pump > Flashcards

CVS - The Heart As A Pump Flashcards

1
Q

What is the difference between resistance and capacitance vessels?

A

Resistance vessels - restrict blood flow to drive supply to hard to perfuse areas of the body, usually arteries.

Capacitance vessels - enable system to vary amount of blood pumped around body, usually veins.

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2
Q

Which has the higher pressure - the systemic or pulmonary circulation?

A

Systemic circulation has high, while pulmonary has low.

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3
Q

What is systole?

A

When the heart contracts and ejects blood from the ventricles

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4
Q

What is diastole?

A

When the heart relaxes and the ventricles fill.

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5
Q

What is the rough amount of blood pumped by each ventricle per beat?

A

About 70 ml

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6
Q

Is a cardiac action potential relatively long or short?

A

Relatively long - lasts for duration of a single contraction of heart (around 280ms)

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7
Q

Which valve regulates flow from left atrium to left ventricle?

A

Mitral valve

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8
Q

Which valve regulates flow from right atrium to right ventricle?

A

Tricuspid valve

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9
Q

Which valve regulates flow out of the right ventricle?

A

Pulmonary valve

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10
Q

Which valve regulates flow out of the left ventricle?

A

Aortic valve

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11
Q

How do the cusps of the mitral and tricuspid valves attach to papillary muscle?

A

Via chordae tendineae, which prevent inversion of valves on systole.

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12
Q

Describe the sequence of electrical conduction in the heart.

A
  • pacemaker cells in SINOATRIAL NODE generate an action potential
  • activity spreads over ATRIA
  • reaches the AV NODE where it is delayed for 120 ms
  • spreads down SEPTUM between ventricles
  • spreads through VENTRICULAR MYOCARDIUM from inner to outer epicardial surface
  • ventricle contracts from BASE up
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13
Q

What are the seven 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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14
Q

When the heart rate increases, what happens to the length of systole and diastole?

A

Systole remains the same, diastole shortens

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15
Q

What does a Wiggers diagram show?

A

It illustrates the co-ordination of the cardiac cycle, using:

  • aortic pressure
  • left ventricular pressure
  • left atrial pressure
  • left ventricular volume
  • ECG
  • phonocardiogram (heart sounds)
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16
Q

What is the relationship between left ventricle volume and left ventricle pressure?

A

As pressure increases, volume decreases. Aortic pressure also increases simultaneously.

17
Q

What happens in phase 1 of heart contraction?

A

ATRIAL CONTRACTION

Atrial pressure rises due to atrial systole - this is called the ‘A wave’. Ventricular volume peaks.

18
Q

What happens in phase 2 of heart contraction?

A

ISOVOLUMETRIC CONTRACTION

  • mitral valve closes, but aortic valve still closed so volume does not change
  • first heart sound (S1) caused by closing of valves
  • QRS complex in ECG and C wave in atrial pressure curve
19
Q

What happens in phase 3 of heart contraction?

A

RAPID EJECTION

  • ventricular pressure higher than in aorta so aortic valve opens
  • ventricles contract
  • atrial pressure initially decreases as atrial base is pulled downwards as ventricle contracts (‘X descent’)
20
Q

What happens in phase 4 of heart contraction?

A

REDUCED EJECTION

  • repolarisation of ventricle causes rate of contraction to fall
  • atrial pressure rises (‘V wave’)
  • T-wave of ECG
21
Q

What happens in phase 5 of heart contraction?

A

ISOVOLUMETRIC RELAXATION

  • brief backflow of blood into ventricle is stopped by aortic valve (dicrotic notch)
  • rapid decline in ventricular pressure but volume remains constant as all valves are closed (these cause second heart sound - S2)
22
Q

What happens in phase 6 of heart contraction?

A

RAPID FILLING

  • fall in atrial pressure after mitral valve opens (Y-descent)
  • third heart sound (S3) present in children and occasionally (abnormally) in adults
23
Q

What happens in phase 7 of heart contraction?

A

REDUCED FILLING

  • rate of filling slows as ventricle reaches inherent relaxed volume
24
Q

What is aortic valve stenosis?

A
  • valve doesn’t open enough, so less blood can get through
  • can lead to increased LV pressure -> LV hypertrophy
  • can lead to left sided heart failure -> syncope, angina
  • shear stress can damage erythrocytes
25
Q

Give some causes of aortic valve stenosis.

A
  • degenerative (senile calcification/fibrosis)
  • congenital
  • chronic rheumatic fever
26
Q

Give some causes of aortic valve regurgitation

A
  • aortic root dilation

- valvular damage

27
Q

What is it called when a valve doesn’t close all the way?

A

Regurgitation

28
Q

What is it called when a valve doesn’t open enough?

A

Stenosis

29
Q

What are the effects of aortic valve regurgitation?

A
  • blood flows back into LV during diastole, which increases stroke volume
  • systolic pressure increases, diastolic pressure decreases
30
Q

Give some symptoms of aortic valve regurgitation

A
  • bounding pulse (head bobbing, Quinke’s sign)

- LV hypertrophy

31
Q

Give some causes of mitral valve regurgitation

A
  • Myxomatous degeneration can weaken tissue leading to prolapse
  • damage to papillary muscle
  • left sided heart failure
  • rheumatic fever
32
Q

How does mitral valve regurgitation cause LV hypertrophy?

A

Some blood leaks back into LA, which increases pre-load and can cause LV hypertrophy

33
Q

What is the main cause of mitral valve stenosis?

A

Rheumatic fever

34
Q

What does increased LA pressure due to mitral valve stenosis cause?

A
  • pulmonary oedema, dyspnea and pulmonary hypertension which can lead to RV hypertrophy
  • LA dilation, which can lead to:
  • atrial fibrillation -> thrombus formation
  • oesophagus compression -> dysphagia

ESA 2 SEMESTER 2 TK (87 decks)

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