Question

what is a cardiac cycle

Answer 1

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here's your answer,
CARDIAC CYCLE: The cardiac cycle consists of one heart beat or one cycle of contaction and relaxation of cardiac muscle.

During a heart beat, there is contraction and relaxation of atria and ventricles.

The contraction phase is called the systole while the relaxation phase is called diastole.

When both atria and ventricles are in diastolic or relaxed phase, this is refered as JOINT DIASTOLE.

During this phase, the blood flows from the superior and the inferior venacava into the atria and from the atria to the respective ventricles through auriclo ventricular valves.

(But there is no flow of blood from ventricles into arota and pulmonary trunk as the semilunar valves remain closed)

The successive stages of the cardiac cycle are briefly described below,

#ATRIAL SYSTOLE : The atria contract due to a wave of contraction, stimulated by the SA node. The blood is forced into the ventricles as the bicuspid and tricuspid valves are open.

#BEGINNING OF VENTRICULAR SYSTOLE: The ventricles began to contract due to aa wave of contraction, stimulated by the AV node. The bicuspid nad tricuspid valves close immediately producing part of the FIRST HEART SOUND.

#COMPLETE OF VENTRICULAR SYSTOLE: When the ventricles complete their contraction,the blood flows into the pulmonary trunk and aorta as the semilunar valves open.

#BEGINNING OF VENTRICLUAR DIASTOLE: The ventricles relax and the semilunar valves are closed. This causes the SECOND HEART SOUND.


#COMPLETE VENTRICULAR DIASTOLE: The tricuspid and the bicuspid valves open when the pressure in the ventricles falls and blood flows from the atria into the ventricles. ContractionContraction of the heart doesnot cause this blood flow. It is due to the fact that the pressure within the relaxed ventricles is less than that in the atria and veins.


the duration of cardiac cycle is 0.8 seconds.
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HOPE THIS HELPS YOU ❤
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Answer 2

The cardiac cycle is the sequence of events that occur when heart beats. This cycle has two main phases
1. Diastole, when the heart ventricles are relaxed and
2. Systole, when the ventricles contract.

One cardiac cycle is defined as the contraction of the two artia followed by contraction of the two ventricles