CH18 W6: Cardiac Cycle

When a chamber is contracting, it is said to be in:

Systole

When a chamber is relaxing and filling, it is said to be in:

Diastole

In a resting cardiac cycle, describe how much time is spent in each phase

⅓ (33%) time in systole (squeeze)

⅔ (66%) time in diastole (filling)

What is the point of Wiggers diagram?

It puts everything on one page so you can see which events happen simultaneously.

(link all happenings of one heartbeat cardiac cycle on one graph)

If the volume decreases, the pressure:

Increases

If the chamber contracts, the pressure:

Increases

If the chamber relaxes, the volume increases and the pressure:

Decreases

Describe the relationship between volume and pressure

Inverse (Volume compartment ↓ = Pressure ↑)

When you see the P wave on the ECG, what is happening with atrial pressure?

Atria is squeezing, pressure goes up

When the atria are squeezing, describe the state of the AV valves?

Valves are open so blood can push into ventricles

When the ventricle is full of blood that volume is called the:

End diastolic volume (EDV)

When you see the QRS complex on the ECG, what happens to ventricle pressure?

Pressure goes up, numbers get higher

When ventricle pressure goes up, which valves CLOSE?

Tricuspid and bicuspid (AV valves close)

Which heart sound corresponds to QRS complex on ECG?

1st , called LUB

When ventricle pressure exceeds aortic pressure, what happens?

Semilunar valves open, blood pumped into aorta

Is there any marker for where the aortic and semi-lunar valves open on the graph?

Yes, where ventricle pressure exceeds aortic pressure (blue crosses green)

What happens to the pressure in the aorta as blood is ejected?

Pressure goes up to 120 mmHg

The amount of blood pumped out of the ventricle during a heart beat in mls is called the:

Stroke volume (SV)

The amount of blood which remains in the ventricle after squeezing is called the:

End systolic volume (ESV)

If the EDV is 120 mls and the ESV is 30 mls, what is the SV?

120 - 30 = 90 mls

If the EDV is 120 mls and the SV was 70, what is the ESV?

120 - 70 = 50 mls

SV = EDV - ESV

The stroke volume (SV) is the difference between the end-diastolic volume (EDV) and the end-systolic volume (ESV).

When you see T wave on ECG, what happens to ventricular cardiac muscle?

Ventricles relax, go into diastole

When you see T wave, what happens to ventricular pressure?

Ventricular pressure drops to 0

When pressure in the ventricle falls below pressure in the aorta, what happens?

The semilunar valve closes

Which heart sound will correspond with the end of the T-wave?

2nd , the DUB

When you hear the second heart sound, which artefact is visible on the aortic pressure trace?

Dicrotic notch

When do the AV valves open?

When Pressure in ventricles goes lower than pressure in atrium

Is there any place on the graph we could pinpoint as the location of AV valve opening?

Yes, where blue line goes below purple line, they cross

Valves can be described as

Passive movers (Flaps of CT can’t move on own)

Are papillary muscles involved with valve opening or closing?

Neither! It just keeps it closed. 

What is the point of papillary muscles?

They hold the valve in the closed position so it does not invert. So they don’t close the valve, but they do keep it closed when it is closed. (Keep valve closed when ventricle pressure is very high)

So papillary muscles will contract when in:

Ventricular systole (high pressure)