Cardiac Cycle

ABP = SV x HR x TPR

So impulses spread rapidly.

Pressure will increase in a chamber when the muscle wall around it contracts. Valves will open when there is a pressure gradient across them. Blood will flow down a pressure gradient, when the valves are open, pressures in the neighbouring chambers change together. When the valves are closed, pressures in the neighbouring chamber can be different.

Rapid filling. A-V valve is open because the atrial pressure is greater than ventricular. The aortic valve is closed because the ventricular pressure is lesser than the aortic. Pulmonary vein pressure is greater than atrial and ventricular. The atrial contraction increases pressure contributes around 5ml of ventricular filling (very little).

Isovolumetric contraction. Ventricular contraction increases ventricular pressure. When the ventricular pressure is greater than atrial pressure the AV valve closed. Aortic valve is closed and opens when the ventricular pressure is greater than the aortic pressure when the ventricle contracts and ejects into aorta.

Ventricle relaxes deceasing the pressure and the aortic valve closes. A-V valve are closed as the ventricular pressure is greater than the atrial pressure. When the atrial pressure increases the A-V valves open.

3

2

End diastolic volume - end systolic volume

You need to shorten the rate of the cardiac cycle by stimulating the p wave sooner. The p wave can move a long way to the left before ventricular filling is comprised.

Pressures are much lower in the right side of the heart than left, nearly half the pressure. aorta = 120/80 pulmonary artery = 25/10 left artery = 8 Left ventricle = 120/8 right artery = 4 right ventricle = 25/4

pressure / resistance.

Because it needs to reach high pressures to pump the blood further.