2011生理学第7版血液循环课件.ppt

（二）Rh血型系统 二、心脏泵血功能的评定 每博输出量 stroke volume 一次心博中，由一侧心室射出的血液量 射血分数 ejection fraction =（每博输出量/心室舒张末期容积）×100% 心输出量（心排血量）cardiac output =每博输出量×心率 静息心指数（心排血指数）cardiac index =静息空腹时心输出量/体表面积 复习影响横纹肌收缩效能的因素 1、前负荷 2、后负荷 3、肌肉的收缩能力 contractility 心室舒张末期充盈量 静脉回心血量 心缩末期容积 3、心肌收缩能力 myocardial contractility 2、心肌收缩能力 contractility 3、后负荷对博出量的影响 The cardiac cycle The cardiac cycle is divided into two major phases, both named for events in the ventricles: the period of ventricular contraction and blood ejection, systole, followed by the period of ventricular relaxation and blood filling, diastole. The cardiac output The volume of blood pumped by each ventricle per minute is called the cardiac output (CO), usually expressed in liters per minute. It is also the volume of blood flowing through either the systemic or the pulmonary circuit per minute. The cardiac output is calculated as heart rate (HR) times stroke volume (SV). The cardiac output The first variable that determines cardiac output is Heart rate, the number of beats per minute . The second variable that determines cardiac output is stroke volume, the blood volume ejected by each ventricle with each beat. The stroke volume The ventricles do not completely empty themselves of blood during contraction. Therefore, a more forceful contraction can produce an increase in stroke volume by causing greater emptying. Changes in the force of contraction can be produced by a variety of factors, but three are dominant under most physiological and pathophysiological conditions: (1) preload; (2) contractility; (3) afterload. Pacemaker potential The cell potential in the SA node is a pacemaker potential. These cells do not have a constant resting potential. Instead, they slowly depolarize immediately after each repolarization, the most negative value of which is the maximum diastolic potential (MDP, ca. –70 mV). The slow diastolic depolarization or prepotential (PP) preva