Cardiac Cycle and Cardiac Output

What is occurring during late ventricular diastole (or "complete diastole")?

All chambers of the heart are relaxed. The AV valves are open and semilunar valves are closed. Blood is passively filling the ventricles.

If you wanted a high stroke volume, what would you want from the EDV and ESV?

Higher EDV, lower ESV.

If you wanted a higher cardiac output, what all would you do?

Increase muscle activity and respiratory rate, increase sympathetic activity to the SA node to increase heart rate and to the ventricles to increase contraction force.

What two factors most effect the strength of ventricular contraction?

Sympathetic activity to the ventricles will increase force of contraction. Regular cardiovascular activity will increase the strength of the cardiac muscle tissue.

What generates the first heart sound (the "lub")?

The AV valves shutting when the ventricles begin contraction.

What is the end diastolic volume?

The amount of blood found in the ventricles just before contraction.

What is the end systolic volume?

The amount of blood left in the ventricles after contraction.

What is cardiac output?

The amount of blood pumped out of the heart in a given unit of time.

What is the "stroke volume"?

The amount of blood pumped out of the ventricles in a single cardiac cycle.

What factor most effects the EDV?

The amount of venous return.

What two factors effect stroke volume?

The end diastolic volume and the end systolic volume.

How can venous return be altered?

The increasing or decreasing muscle activity and respiratory rate.

What generates the second heart sound (the "dub")?

The semilunar valves shutting when the ventricles relax.

What factor most effects the ESV?

The strength of ventricular contraction.

What two factors determine cardiac output?

The stroke volume and the heart rate.

Why can an athlete have a lower heart rate at rest than a non-athlete?

They have a higher stroke volume due to a stronger heart contraction and therefore lower ESV at all times so at rest the stroke volume can compensate for the lowered heart rate.

What is occurring during early ventricular diastole?

Ventricles begin to relax. Blood falls back on the semilunar valves as the pressure drops in the ventricles causing the closing of the semilunar valves.

What is occurring during late ventricular systole?

Ventricles contract with more force and semilunar (pulmonary and aortic) valves open. Blood is forced into the aorta and pulmonary trunk.

What is occurring during atrial systole?

atria contract and force blood past the AV valves and into the ventricles. Ventricles are relaxed.

What is occurring during early ventricular systole?

atria relax and ventricles begin to contract. AV valves shut.