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Anatomy and Physiology II-Cardiac cycle
What is the cardiac cycle?
1) ventricular filling
2) isovolumetric contraction
3) ventricular ejection
4) Isovolumetric relaxation
relationship between pressure and volume
Inversely related, as one goes up, the other goes down
What happens during ventricular filling
Ventricular muscle relaxes, intraventricular volume increases and pressure drops below atrial pressure. AV valves open as blood flows into the ventricles, atria contract to top off the ventricles.
When do the atrium contract?
When does the AV valve open?
What happens during isovolumetric contraction?
Systole begins, but no blood pumped out of the ventricles yet, pressure rises in ventricles, AV valves close to prevent backflow into atria
When do AV valves close?
during isovolumetric contraction
What happens during ventricular ejection?
Ventricles continue to contract, pressure in ventricles rise above the pressure in aorta and pulmonary artery, semilunar valves open, blood moves out of ventricles
When does blood move out of ventricles?
The ejection fraction
The amount of blood pumped out of the ventricles (usually about 60%)