The cardiac cycle refers to the repetitive pumping process that begins with the onset of cardiac muscle contraction and ends with the beginning of the next contraction. There are two important terms to memorize when talking about this cycle: systole and diastole.? Systole refers to contraction. Atrial systole refers to the contraction of the atria at the beginning of the heart cycle. Diastole refers to relaxation. Ventricular diastole refers to the relaxation of the ventricles after pumping. ??注釋： ??cardiac cycle /?kɑ?d??k ?sa?k(?)l/ 心動周期；心搏周期 ??repetitive /r??p?t?t?v/ 重復的 ??pump /p?mp/ 泵；用泵(或泵樣器官等)輸送；抽運；抽吸 ??onset /??ns?t/ 開始；發(fā)作 ??cardiac muscle /?kɑ?d??k ?m?s(?)l/ 心肌 ??contraction? /k?n?tr?k??n/ 收縮；縮小 ??term /t??m/ 術語；詞語；措辭 ??systole /?s?st?l?/? (心臟)收縮；心縮期 ??diastole? /da???st?l?/ (心臟)舒張；心舒期 ??atrial systole /?e?tr??l ?s?st?l?/ 心房收縮(期) ??atrium /?e?tr??m/? 心房 (復數(shù)atria /?e?tr??/ 或 atriums) ??heart cycle 心搏周期 ??relaxation /?ri?l?k?se???n/ 放松；休息；消遣 ??ventricular diastole /v?n?tr?kj?l? da???st?l?/ 心室舒張(期)