Physiology: Cardiac Cycle & Hemodynamics

What is the mathematical formula used to calculate Cardiac Output (CO)?

Cardiac Output = Heart Rate (HR) × Stroke Volume (SV)

Which heart sound is produced by the closure of the atrioventricular (mitral and tricuspid) valves?

The first heart sound (S1)

In cardiac physiology, how is 'Preload' defined?

Preload is the initial stretching of the cardiac myocytes prior to contraction, usually approximated by the End-Diastolic Volume (EDV).

Which heart sound marks the beginning of ventricular diastole and is caused by the closure of the semilunar valves?

The second heart sound (S2)

What is the primary factor that determines 'Afterload' for the left ventricle?

Systemic vascular resistance or the pressure the ventricle must overcome to eject blood (Aortic pressure).

During which specific phase of the cardiac cycle are all four heart valves closed while ventricular pressure rises rapidly?

Isovolumetric contraction

According to the Frank-Starling mechanism, what happens to the stroke volume as the end-diastolic volume increases?

Stroke volume increases due to the increased stretch of the myocardial fibers, leading to a more forceful contraction.

What effect does sympathetic nervous system stimulation have on cardiac contractility (inotropy)?

It increases contractility by increasing intracellular calcium concentration during systole.

During which phase of the cardiac cycle does the majority of ventricular filling occur?

The early, passive filling phase of diastole.

How is Mean Arterial Pressure (MAP) calculated using systolic (SBP) and diastolic (DBP) blood pressures?

MAP = DBP + 1/3(SBP - DBP)