生理复习----血液循环(英文版).docVIP

Chapter4 cardiovascular system Section one Pump function of heart I. Cardiac Cycle 1.cardiac cycle:The period of one contraction and one relaxation of the heart. 2.cardiac cycle＝60s／heart rate;heart rate:75beats/min,so cardiac cycle is 0.8sec. 3.A cardiac cycle consists of a systole(收缩期) and a diastole(舒张期).When heart beat becomes more rapid, the heart cycle is shorter, and the diastole is much shorter than normal. 4.ventricular systole:isovolumic contraction(Enable the ventricular pressure to rise from 0 to the level of aortic pressure)，rapid ejection，slow ejection. 5.ventricular diastole:isovolumic relaxation(Enable the ventricular pressure fall to the level near the atrial pressure),rapid filling,slow filling,atrial systole. 6.Heart sound (1)first sound:caused by closure of the atrioventricular valves,marks the beginning of ventricular systole. (2)second heart sound:caused by closure of the aortic and pulmonary valves,marks the beginning of ventricular diastole. II. Cardiac Output 1.Stroke volume (1)concept:The amount of blood pumped out of each ventricle per beat is called the stroke volume, about 70mL in a resting adult. (2)stroke volume(70mL)＝end-diastolic volume(125)－end-systolic volume(55mL) 2.Ejection fraction(55%~65%)＝stroke volume(70mL)／end-diastolic volume(125mL) 3.cardiac output(心输出量) (1)The output of each ventricle per minute is called the cardiac output. (2)It varies with sex,age,and exercise.About 4.5~6.0L/min in a resting healthy man. 4.cardiac index(心指数) (1)concept:The output per minute per square meter of body surface is known as the cardiac index. (2)the normal range is: 3.0 – 3.5 L/min·m2 III. Factors Affecting Cardiac Output ①Preload(前负荷),②Afterload(后负荷),③myocardinal contractility(心肌收缩能力),④heart rate. 1.Preload(前负荷)------ventricular end-diastolic volume(心室舒张末期容积) (1)end-diastolic volume↑→initial length in cardiac muscle↑→contractility↑→stroke volume↑. (2)optimal initial preload(length) is 2.0~2.2μm. (3)factors det