The cardiac cycle at the point of beginning a ventricular<unk> , or contraction: 1) newly oxygenated blood (red arrow) in the left ventricle begins pulsing through the aortic valve to supply all body<unk> ems; 2) oxygen-depleted blood (blue arrow) in the right ventricle begins pulsing through the pulmonic (pulmonary) valve en route to the lungs for reoxygenation. P wave depolarization is the start-point of the atrial stage of<unk> . The ventricular stage of<unk>  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. The<unk>  ( ) is the part of the cardiac cycle during which some chambers of the heart muscle contract after refilling with blood. The term originates, via New Latin, from Ancient Greek (sustolē), from (sustéllein 'to contract'; from sun 'together' + stéllein 'to send'), and is similar to the use of the English term to squeeze. The mammalian heart has four chambers: the left atrium above the left ventricle (lighter pink, see graphic), which two are connected through the mitral (or bicuspid) valve; and the right atrium above the right ventricle (lighter blue), connected through the tricuspid valve. The atria are the receiving blood chambers for the circulation of blood and the ventricles are the discharging chambers. When, in late ventricular diastole, the atrial chambers contract, they send blood down to the larger, lower ventricle chambers. When normal flow is completed, the ventricles are filled and the valves to the atria are closed. The ventricles now perform<unk>  isovolumetrically, which is contraction while all valves are closed—ending the first stage of<unk> . The second stage proceeds immediately, pumping oxygenated blood from the left ventricle through the aortic valve and aorta to all body<unk> ems, and simultaneously pumping oxygen-poor blood from the right ventricle through the pulmonic valve and pulmonary artery to the lungs. Thus, the pairs of chambers (upper atria and lower ventricles) contract in alternating sequence to each other. First, atrial contraction feeds blood into the ventricles, then ventricular contraction pumps blood out of the heart to the body<unk> ems, including the lungs for resupply of oxygen. Cardiac<unk>  is the contraction of the cardiac muscle in response to an electrochemical stimulus to the heart's cells (cardiomyocytes). Cardiac output (CO) is the volume of blood pumped by the each ventricle in one minute. The ejection fraction (EF) is the volume of blood pumped divided by the total volume of blood in the left ventricle.
Systole
Acremonium
Creatine
Bromide
Beta-Hydroxy beta-methylbutyric acid
Adenosine
Choline
Adrenaline