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Cardiovascular > Cardiac Cycle > Flashcards

Cardiac Cycle Flashcards

1
Q

What is responsible for the closing and opening of the AV and semilunar valves?

A

Passive process due to the pressure difference across the valve
(Atrial pressure > ventricular pressure) - AV
(Ventricular pressure > aortic/pulmonary pressure) - Semilunar

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2
Q

Define the cardiac cycle and types of events.

A 
One complete set of cardiac contraction and relaxation. 
Consists of the mechanical events (volume and pressure changes) 
Electrical events (ECG)
Valvular events (heart sounds)
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3
Q

Describe how the time is spent in either diastole/systole.

A

Normally 2/3 diastole, 1/3 systole

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4
Q

What happens to the time in diastole and systole when the heart rate increases?

A

With an increase in heart rate, diastole will be cut down and therefore the heart spends less time in the filling phase.

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5
Q

Name the phases involved in diastole.

A

Isovolumetric/Isometric Ventricular Relaxation (0.05s)

Passive Ventricular Filling (0.5s)

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6
Q

Describe isovolumetric/isometric ventricular relaxation.

A

After ventricular contraction, there is a reduction in pressure. ALL VALVES ARE SHUT.
Ventricular volume is at a minimum (ESV - end systolic volume)
No change in the volume of blood in the ventricles
Atria are filling with blood returning to the heart, atrial pressure < ventricular pressure

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7
Q

Describe ventricular filling (0.5s)

A

Atrial pressure is greater than ventricular pressure
AV valves open causing atrial accumulation to move passively into the ventricles
Volume in ventricles is at a max = EDV (130ml)

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8
Q

Name the two phases of systole.

A 
Isovolumetric (Isometric) Contraction (0.05s) 
Ventricular Ejection (0.3s)
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9
Q

Describe Isovolumetric (Isometric) Contraction

A

Ventricle pressure > atrial pressure, but less than aortic/pulmonary pressure
AV valves snap shut = S1 sound
Tension builds in fibres to increase pressure
Takes 0.05s

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10
Q

Describe Ventricular Ejection

A 
LVP > AP 
RVP > PAP 
SL valves open 
Blood is ejected
Lasts about 0.3s
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11
Q

Describe what happens after ventricular ejection.

A

Pressure in ventricles decreases to be less than aortic and pulmonary pressure. SL valves close = S2 sound.
Goes back to ESV, starts isovolumetric/isometric ventricular relaxation.

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12
Q

What are the phases of diastole?

A

Isovolumetric (isometric) relaxation and ventricular filling

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13
Q

What are the phases of systole?

A

Isovolumetric contraction and ventricular ejection

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14
Q

When is ventricular volume at a max and a min?

A

Maximum at EDV

Minimum at ESV

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15
Q

Name the two phases which the cardiac cycle is divided into.

A

Ventricular diastole: ventricles are relaxed

Ventricular systole: ventricles are contracting

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16
Q

How long is isovolumetric ventricular relaxation?

A

0.05s

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17
Q

How long is ventricular filling?

A

0.5s

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18
Q

How long is isovolumetric ventricular contraction?

A

0.05s

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19
Q

How long is isovolumetric ventricular relaxation?

A

0.05s

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20
Q

How long is ventricular ejection?

A

0.3s

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21
Q

Name the events taking place in the cardiac cycle.

A 
Electrical events (ECG) 
Mechanical events (volume and pressure changes) 
Valvular events (opening and closing - heart sides)
22
Q

Describe what happens to ventricular volume.

A

Maximum at end of diastole (EDV)
Constant during isometric ventricular contraction
Falls rapidly during ventricular ejection
Minimum at the end of ventricular systole (ESV)
Constant during isometric ventricular relaxation

23
Q

When is ventricular pressure at a minimum?

A

Beginning of diastole

24
Q

Describe what happens to ventricular pressure during ventricular filling and after atrial contraction?

A

Ventricular pressure rises a little

25
Q

When does ventricular pressure rise dramatically?

A

During isometric contraction (systole)

26
Q

Describe what happens to ventricular pressure during the ejection phase of systole.

A

Continues to rise to a maximum during the ejection phase then falls during late systole

27
Q

What happens in isovolumetric relaxation with regards to ventricular pressure?

A

Falls dramatically to a minimum valve

28
Q

When is arterial pressure at a minimum?

A

End of diastole (diastolic pressure)

29
Q

When does arterial pressure rise to a maximum?

A

During the ejection phase (systolic pressure)

30
Q

What happens when the ventricular pressure falls below the arterial pressure?

A

Aortic valve closes (S2)

31
Q

How do we calculate arterial pulse pressure?

A

SP - DP

32
Q

How do we calculate SV?

A

EDV - ESV

33
Q

What are the differences between the right side of the heart and the left side of the hear

A

Right ventricular volumes = left ventricular volumes
Pulmonary resistance is lower than total peripheral resistance (systemic circulation)
Right ventricular and pulmonary artery pressures are lower than the left ventricular pressure and aortic pressure

34
Q

Name the three waves of right atrial pressure.

A

A
C
V

35
Q

Describe the importance of knowing that there are no valves between the right atrium and vena cavae.

A

Pressure changes in the right atrium are transmitted back into the large veins - jugular venous column.
Can see the A C and V waves in the jugular venous column.

36
Q

What do we use the JVP for?

A

To assess right atrial pressure

37
Q

What is the normal HR and cardiac cycle duration at rest?

A

Heart rate - 60bpm

Cardiac cycle duration - 1s (2/3 diastole, 1/3 systole)

38
Q

What happens to diastole and systole as HR increases?

A

Both diastole and systole duration decrease

But diastole decreases more than systole to preserve systolic time

39
Q

What does the P wave indicate about the cardiac cycle?

A

Atrial depolarization - precedes atrial contraction

40
Q

What does the QRS complex indicate about the cardiac cycle?

A

Ventricular depolarization - precedes ventricular contraction

41
Q

What does the T wave show?

A

Ventricular repolarization

42
Q

Which events occur first?

A

Electrical events precede mechanical events

43
Q

What causes the first heart sound?

A

Closure of the mitral and tricuspid valves

M1 before T1

44
Q

What does the first heart sound sound like?

A

Lubb

45
Q

Which AV valve closes first?

A

Mitral before tricuspid

46
Q

What causes the second heart sound?

A

Closure of semilunar valves
Aortic closes before pulmonary
Dubb

47
Q

What causes the third heart sound?

A

Rapid ventricular filling early diastole

48
Q

When may the third heart sound be heard?

A

In the young or those with LVF

49
Q

What causes S4?

A

Ventricular filling in atrial top up
indicates reduced ventricular compliance
Gallop rhythm

50
Q

What causes murmurs?

A

Turbulent blood flow
Narrowing of a valve - stenosis
Reversal of flow through a valve - valve insuffiency or incompetence
Murmurs are an important sign of valve lesions

51
Q

When does the murmur occur in aortic stenosis?

A

Between S1 and S2

52
Q

When does the murmur occur in mitral incompetence?

A

Throughout systole

Cardiovascular (11 decks)

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