exam 2: cardiac cycle (mechanisms, sounds/murmurs)

Cardiac cycle

The sequence of electrical and mechanical events that occur during one heartbeat.

Electrical and mechanical events responsible for atrial and ventricular contraction

Two main phases of the cardiac cycle

• diastole: ventricles relax & fill with blood

• systole: ventricles contract & pump blood out

What is the goal of the cardiac cycle?

To move blood efficiently through the heart & into circulation

What happens during late diastole and ventricular contraction regarding pressure changes, AOV, and s2?

Wigger’s diagram

Pressure relationship between left sided heart chambers (increase in pressure on L side)

Diastole

The phase of ventricular relaxation and filling

Diastole

The phase of ventricular relaxation and filling

What veins do the atria receive blood form?

The atria receive blood returning from the systemic veins (RA) and the pulmonary veins (LA)

How does blood move from the atria to the ventricles during diastole and what effect does it have on ventricular pressure?

• Blood flows through the open AV valves (MV, TV) and into the ventricles

• Ventricular filling increases diastolic pressure within the ventricles

What occurs during late diastole and what is the “a” wave?

During late diastole, the atria contract and push the final bolus (part) of blood into the ventricles (atrial kick). This atrial contraction causes a rise in atrial pressure, which appears as the “a” wave on the Wiggers Diagram.

What marks the onset of ventricular systole?

Ventricular contraction begins, causing ventricular pressure to exceed atrial pressure