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Electrical waves track a systole (a contraction) of the heart. The end-point of the P wave depolarization is the start-point of the atrial stage of systole. The ventricular stage of systole begins at the R peak of the QRS wave complex; the T wave indicates the end of ventricular contraction, after which ventricular relaxation (ventricular diastole) begins.
Ventricular systole is the contractions, following electrical stimulations, of the ventricular syncytium of cardiac muscle cells in the left and right ventricles. Contractions in the right ventricle provide pulmonary circulation by pulsing
The period of time that begins with contraction of the atria and ends with ventricular relaxation is known as the cardiac cycle. The period of contraction that the heart undergoes while it pumps blood into circulation is called systole. The period of relaxation that occurs as the chambers fill with blood is called diastole.
It is caused by the closure of the atrioventricular valves, i.e. tricuspid and mitral (bicuspid), at the beginning of ventricular contraction, or systole. When the ventricles begin to contract, so do the papillary muscles in each ventricle.
Wiggers diagram of the cardiac cycle, with isometric contraction marked at upper left. In cardiac physiology, isometric contraction is an event occurring in early systole during which the ventricles contract with no corresponding volume change (isometrically). This short-lasting portion of the cardiac cycle takes place while all heart valves ...
Afterload, or how much pressure the heart must generate to eject blood at systole, is influenced by vascular resistance. It can be influenced by narrowing of the heart valves or contraction or relaxation of the peripheral blood vessels. [8] The strength of heart muscle contractions controls the stroke volume.
Coordinated contraction of ventricular cells. The ventricles must maximize systolic pressure to force blood through the circulation, so all the ventricular cells must work together. Ventricular contraction begins at the apex of the heart, progressing upwards to eject blood into the great arteries.
EF is the fraction of blood ejected by the left ventricle (LV) during the contraction or ejection phase of the cardiac cycle or systole. Prior to the start of systole, during the filling phase , the LV is filled with blood to the capacity known as end diastolic volume (EDV). During systole, the LV contracts and ejects blood until it reaches its ...