The Cardiac Cycle Flashcards

1
Q

At what point is diastolic pressure measured?

A

Diastolic pressure is measured in the arteries at the end of the ventricular filling phase. I.e. just before the mitral valve closes

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2
Q

When is systolic pressure measured?

A

Systolic pressure occurs at the height of ventricular contraction when ventricular and aortic pressure are at their highest.

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3
Q

What are ICP?

A

ICP = Isometric Contraction Phase. Between mitral valve closing and aortic valve opening. The ventricle is contracting but no blood is moving in or out so pressure climbs.
Start of Systole

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4
Q

What is the IRP?

A

Isometric Relaxation Phase
Between Aortic Valve closing and Mitral Valve opening again. The ventricle is relaxing but no blood is moving in or out.
Start of Diastole

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5
Q

What is the pulse pressure?

A

The difference between the diastolic and systolic pressures. (~40mmHg at rest)

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6
Q

What is mean arterial pressure?

A

The average arterial pressure throughout a cardiac cycle.
As a rule of thumb its diastolic + 1/3 pulse pressure.

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7
Q

On a pressure time graph the atrium has 3 waves a, c & v. What are they?

A

a - equates to the p wave on an ECG. And the active filling phase of diastole. This is where the atrium contracts to force a little extra blood into the ventricle, hence the brief increase in atrial pressure.
c - During ICP when ventricular pressure climbs causing the mitral valve to briefly balloon back into the atrium causing an atrial pressure increase
v - steady rise in atrial pressure after the c wave as venous blood from lungs fills the atrium. Stops at the end of IRP when the mitral valve opens and blood can flow into the ventricle.

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8
Q

What is the End Diastolic Volume?

A

The max ventricular volume at the end of diastole. (EDV)

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9
Q

What is the end systolic volume?

A

The min ventricular volume at the end of systole. (ESV)

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10
Q

What is stroke volume?

A

The differnece between the EDV & ESV. Essentially how much blood is pumped out in each cycle.

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11
Q

What is the ejection fraction?

A

The Stroke Volume over End diastolic volume. (SV/EDV).
Should be around 2/3 in a healthy heart.

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12
Q

How is the ejection phase divided?

A

Ejection phase is all the time th eaortic valve is open and blood flows out the ventricle into the artery. (most of systole)
The first 3rd is the rapid ejection phase
The last two 3rds are the slow ejection phase.

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13
Q

How is the filling phase divided?

A

All the time the mitral valve is open and blood flows into the ventricle. (Most of diastole)
First 3rd - Rapid filling phase
Second 3rd - Slow filling phase
Third 3rd - Active filling Phase. When the atrium contracts to force the last bit of blood into the ventricle.

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14
Q

There are 4 heart sounds during the cardiac cycle that are audible due to turbulence in the blood. What is the 1st?

A

The sound of the mitral valve and tricuspid valve closing at the start of systole

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15
Q

What is the 2nd heart sound?

A

The sound of aortic & pulmonary valves closing during the IRP

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16
Q

What is the 3rd heart sound?

A

The sound of the rapid filling phase

17
Q

What is the 4th heart sound?

A

The sound of the active fillin phase

18
Q

How does the cadiac cycle in the right side compare to that in the left side of the heart?

A

The right side is very similar.
The volumes involved are identical but the pressure is about 1/5 in the right side compared to the left.

19
Q

What happens to the cardiac cycle as the heart rate climbs?

A

Diastole shortens, i.e. the filling phase

20
Q

Why isnt the output affected as the heart climbs to 150BPM

A

Because most of the filling occurs in the rapid fillin phase which isnt isnt shortened at this heart rate

21
Q

Why is the output reduced above ~150bpm?

A

The filling phase shortens so much it cuts into the rapid filling phase and the EDV significantly decreases, therefore so does the SV.

22
Q

What is a phonogram used for?

A

Detecting heart sounds and any abnormal sounds (murmurs)

23
Q

What would cause a systolic murmer? (between 1st & 2nd heart sounds)

A

Stenosis of aortic/pulmonary valves
Or Regurgitation through the mitral/Tricuspid valves.

24
Q

What could cause a diastolic murmur?

A

Stenosis of mitral/tricuspid valves
Or Regurgitation through aortic/pulmonary valves.

25
Q

What could cause a constant murmur?

A

A septal Defect

26
Q

What is a pressure-volume loop?

A

A way of graphing the cardiac cycle in a ventricle.

27
Q

What is normal blood pressure at resting HR? (75BPM)

A

120/80

28
Q

What is the value of resting pulse pressure?

A

40mmHg

29
Q

What is normal EDV at rest?

A

~140ml

30
Q

What is normal ESV at rest?

A

~60ml

31
Q

What is normal stroke volume at rest?

A

~80ml

32
Q

What should the ejection fraction be in a healthy heart?

A

2/3

33
Q

Now go back and learn the pressure/volume vs time graph and pressure-volume loop.

A

JUST DO IT

34
Q

What is the dicrotic notch

A

A small increase in aortic pressure just after the aortic valve closes.
As aortic pressure exceeds the ventricular pressure theres a slight backflow of blood which causes the aortic valve to close. This results in a slight increase in aortic pressure due to the elastic recoil of the valve.