Correct order the sequence of activation in the cardiac cycle

Page created on October 21, Last updated on October 6, at The structure of the heart The heart consists of four chambers, two atria and two ventricles. The cardiac cycle The cardiac cycle is the sequence of events that occurs during 1 heartbeat. The cardiac cycle consists of two parts: the systole and the diastole. We can divide the cardiac cycle into 7 phases. Phase 1 — isovolumetric contraction: Phase 1 marks the beginning of the systole.

Phase 2 — fast ejection: When the pressure inside the ventricles becomes high enough the semilunar valves will be pushed open, allowing fast ejection of the blood into the pulmonary trunk and the ascending aorta. Phase 3 — slow ejection: Blood continues to be ejected by the ventricles but at a slower rate than in the fast ejection, because the pressure inside the ventricles begins to decrease.

This phase marks the end of the systole. Phase 4 — isovolumetric ventricular relaxation: This phase marks the beginning of the diastole. Phase 5 — rapid ventricular filling: The pressure inside the ventricles has now decreased so much that the ventricular pressure is less than the atrial pressure.

It is during this phase when most blood enters the ventricles from the atria. Phase 6 — slow ventricular filling diastasis : Phase 6 is the longest phase of the cardiac cycle. Phase 7 — atrial systole: During this phase the atria contract, pumping blood through the atrioventricular valves into the ventricles. The semilunar valves are closed. This is the last phase of the diastole. Generators and conductors of impulses in the heart.

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Learn about our Editorial Process. The Cardiovascular System The cardiac cycle is vital to proper cardiovascular system function. Cardiac Cycle Phases The events of the cardiac cycle described below trace the path of blood from when it enters the heart to when it is pumped out of the heart to the rest of the body.

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