Systole is the contracting or pumping phase. It is shorter than diastole.
Both ventricles contract and eject blood into pulmonary artery and aorta via the open aortic and pulmonic valves.
AV valves are closed.
What occurs during diastole?
Diastole is the relaxation or filling phase.
Ventricles are relaxed.
Is are extra heart sounds S3 and S4 normal?
S3 is usually okay in young adults.
S4 is related to pathologic conditions.
What is cardiac output?
It is expressed as CO=SV x HR.
It is the amount of blood the heart pumps to the rest of the body per unit time.
What is stroke volume?
The amount of blood pumped per beat?
Stroke volume can be variable. What affects it?
Preload, afterload, and contractility
What is preload?
The degree of myocardial fiber stretch at the end of diastole and before contraction. Also considered to be the loading condition of the heart at the end of diastole. Increased preload increases CO up to a point.
It is determined by the the amount of blood returning to the heart.
What is afterload?
The pressure and resistance the ventricles must overcome to eject blood from the filled heart.
The main components include: SVR and ventricular wall tension.
Related to BP and blood vessel diameter.
What is contractility?
It is the force of cardiac contraction.
What influences preload?
Heart rhythm (if it's too fast, not enough time to fill)
Right or Left ventricular relaxation
Alteration in afterload. If afterload increases, residual volume increases because the heart cannot fully empty.