血液循环2生理学PPT课件.ppt
82页
Chapter IVblood circulation 内容简介：内容简介： 心脏的生物电活动心脏的生物电活动 心脏生理心脏生理 (Cardiac Physiology) 心脏的泵血功能心脏的泵血功能 血管生理血管生理（（vascular physiology) 心血管活动的调节心血管活动的调节 Section TwoMechanism of heart pump Section OverviewlCardiac circle;lProcess of heart pumping blood;lEstimation of function of heart pumping;lCardiac reserve;lRegulation of heart pumping; Heart rate, (HR)Heart rate, (HR) lThe times of heartbeat in a minute. lNormal value: 60~100 beats/minlHR>100 b/m --- TachycardialHR<60 b/m --- Bradycardia Cardiac circleCardiac circlelDefinition:心脏一次收缩和舒张所构成的机械活动周期。
lConsisting of contraction or systole, relaxation or diastole.lThere is a sequence of systole and diastole of the atrium and ventricle.l心房收缩是一次心动周期的开始 Contraction of ventricleContraction of atriumWhole heart diastolerelaxation of ventriclecardiac cycle ØFirst, atria contraction (0.1s)→Øthen, ventricles contraction(0.3s) →Ølast,all the heart relaxation (0.4s);lAtria contraction and ventricles contraction are not occur simultaneously;lDiastole is longer than systole for both the atrium and ventricle.lCardiac cycle = 60/HRlHR↑， cardiac cycle ↓； diastole ↓more apparently； The process of heart pumping The process of heart pumping Ventricular systole: isovolumic contraction phase （1） ejection phase: rapid ejection phase （2） reduce ejection phase（3） Ventricles diastole: isovolumic relaxation （4） filling phase: rapid filling phase （5） reduced filling phase （6） atrial systole （7） Tricuspid ValveAortic semilunar ValvePulmonary semilunar ValveMitral Valve Ventricular SystolelDuration: 0.05slPressure: aorta>ventricles>atrialValve: A-V closed, Semilunar closedlV- ventricles: not changelBlood current direction: not flowlCharacteristics:ventricular pressure rises drasticallyIsovolumetric ventricular contractionIsovolumetric ventricular contraction Rapid Ventricular EjectionRapid Ventricular EjectionlDuration: 0.1slPressure: ventricles > aortalValve: A-V closed, Semilunar openedlV- ventricles: decreaselBlood current direction: blood ejected into aorta rapidlylCharacteristics:ØP-ventricles reach peakØEjecting volume is 2/3 of the total ejecting Ventricular Systole Reduced Ventricular EjectionReduced Ventricular EjectionlDuration: 0.15slPressure: ventricles < aortalValve: A-V closed, Semilunar openedlV- ventricles: decreaselBlood current direction: blood ejected into aorta slowlylCharacteristics:ØEjecting relies on the momentum（动量） of bloodVentricular Systole Ventricular DiastolelDuration: 0.06~0.08slPressure: aorta>ventricles>atrialValve: A-V closed, Semilunar closedlV- ventricles: not changelBlood current: not flowlCharacteristics: ventricles pressure decreased rapidlyIsovolumetric ventricular relaxationIsovolumetric ventricular relaxation Ventricular DiastolelDuration: 0.11slPressure: aorta>ventricles
SummarySummaryl快速射血期末心室压力最大l减慢射血期内主动脉压力已高于心室内压力l减慢射血期末心室容积最小l舒张末期心室容积最大l心室2/3血液充盈在快速充盈期完成，且是负压抽吸所致，10－30％的血量在心房收缩期完成 Role of atrial on Heart PumpingRole of atrial on Heart PumpinglAccommodating and storing blood from vein•Filling of ventricles depend mainly on the diastole of ventricleslPrimary pump The Assess of function of heart pumpingThe Assess of function of heart pumpinglStroke volume: is the volume pumped out by one ventricle with each beat.l=EDV–ESVl=approximate 125-55=70mllDetermined by the contractibility of cardiac muscle.lThe stroke volume of the left ventricle is the same as that of the right ventricle. EDV ESV SV Ejection fraction Ejection fraction lThe value is equal to the quotient between the stroke volume and EDV.lIs about 55-65％(70/125) in resting state.lEjection fraction is relative constant as SV is always proportional to EDV. Cardiac outputCardiac outputlCardiac output is the volume pumped out by each ventricle per minute.lCO= SV x HRlCO for the healthy human adult at rest: 5.25 liters/min (4.5 to 6L/min for healthy males)lThe cardiac output of the left ventricle is the same as that of right ventricle.lChange with body activities and metabolism condition. Cardiac indexCardiac indexlCardiac index is the cardiac output per square meter of body surface area lNormal values range from 3.0 to 3.5 liter/min/m2Ø(For an adult with average size, body surface area 1.6-1.7 m2)lIt varies with age, gender, metabolic state of the body. Cardiac reserveCardiac reserve Cardiac reserve Cardiac reserve lCardiac reserve means the ability which cardiac output can increase with the demand of organism metabolism.l= Maximum CO- minimal CO Cardiac Reserve Including:Cardiac Reserve Including:Reserve of SV and HR ReserveCO=SV HREDV-ESVSystolic reserveDiastolic reserveHR reserve 增加心舒末期容积约15 ml。
减小心缩末期容积约 35~40 ml Source of Cardiac ReserveSystolic reserve 35~40mlDiastolic reserve (~15ml)HR reserve 5. Regulation of Heart Pumping5. Regulation of Heart Pumping lThe goal: match CO to needØRegulation of the stroke volumeØPreloadØAfterloadØContractilityØRegulation of the HRØNervous regulationØHumoral regulation Regulation of Heart PumpingRegulation of Heart Pumpingl1. The regulation of stroke volumeØEffect of preload on stroke volumeØEffect of afterload on stroke volume ØEffect of contractility on stroke volume 1) 1)．．Effect of preload on stroke volumeEffect of preload on stroke volumelPreload : 肌肉收缩前所负载的负荷.l决定肌肉的初长度（initial length）。
lFor cardiac myocyte , the preload is usually considered to be the end-diastolic pressure (or end-diastolic volume) 1) Effect of preload on stroke volume （ventricle function curve）① EDP在12~15 mmHg为最适前负荷 肌小节2.0 ~ 2.2μm，粗、细肌丝处于最佳重叠，产生的张力最大 ② EDP在6 ~ 15mmHg，EDP ,张力 粗、细肌丝有效最佳重叠 ③ EDP在15~20 mmHg，曲线趋于平坦 静息被动张力，EDP对肌小节影响不大，张力不增加 ④ EDP>20mmHg曲线平坦或轻度下倾，无明显的降支 心肌的可伸展性较小，静息被动张力大，阻止心肌细胞过度拉长使心肌肌小节的初长度一般不会超过2.25~2.30μm意义：意义：可使心脏不致于在前负荷明显增加时出现搏出量和作功能力的下降 2）异长自身调节（heterometric autoregulation）通过心肌细胞本身初长度的改变而引起心肌收缩强度的变化称为~。
生理意义：对搏出量微小变化的精细调节，维持心室射血与静脉回流量的平衡保持心室舒张末期压力和容积在正常范围 It is responsible for the precise regulation, and keep balance between the outputs and inputs of the heart. 3 3））Importance of Heterometric Importance of Heterometric AutoregulationAutoregulationJust remember: "What goes in must come out." 5 5））Affecting Factor of Preload (EDV)Affecting Factor of Preload (EDV)l 静脉回心血量üFilling time of ventricles. (diastole period). ØWith HR, filling time shorten.üSpeed of venous returnØDetermined by Peripheral VP-CVPüVentricular compliance üPericarial pressurel Residue volume after ejection (ESV) 2). Effect of Afterload on Stroke Volume2). Effect of Afterload on Stroke Volumel Afterload是指在肌肉开始收缩时才遇到的负荷或阻力。
l它不增加肌肉的初长度，但能阻碍收缩时肌肉的缩短l In simple terms, the afterload is closely related to the aortic pressure. AP AfterloadThe ventricle will have to generate increased pressure Period of isovolumic contraction Decreases the velocity of cardiac fibers shortening Ejection velocity after the valve opens will be reduced less blood will be ejectedSV question?l在整体条件下，正常人主动脉血压于80~160mmHg范围内变化时，心输出量为什么并无明显改变?lBP →SV减少→左心室残余血量增多→左心室EDV ，通过异长自身调节使心肌收缩增强 →SV l生理意义：在动脉血压升高的一定范围内，仍可维持接近正常的心输出量。
3). Effect of Contractility on Stroke Volume3). Effect of Contractility on Stroke Volume心肌不依赖于负荷而能改变其力学活动（收缩的强度和速度）的内在特性又称为心肌的变力状态（intropic state） l等长自身调节（homeometric autoregulation）：l通过肌肉内部机能状态（心肌收缩能力）的改变而实现的泵血功能调节 凡是影响到兴奋收缩耦联过程的各个环节均可影响心肌的收缩力；如：活化的横桥数目， ATP酶的活性； 胞内Ca2+的浓度等等长自身调节 Affecting factors of contractilityAffecting factors of contractilityl（1） 活化横桥数Ø胞浆中的Ca2+浓度：儿茶酚胺ØCa2+与肌钙蛋白的亲合力：茶碱（钙增敏剂）l（2） 横桥ATP酶活性Ø甲状腺激素和体育锻炼 2. 2. The regulation of the heart rateThe regulation of the heart rateThe HR is the determining factor of cardiac output. l HR: CO=SV×HR； o心率增快（＜心率增快（＜160~180次次/min）） 心率心率↑↑ SV↓ 每每分输出量分输出量↑o心率过快（心率过快（> 160~180次次/min）心率）心率↑↑↑ SV↓↓↓↓ 每分输出量每分输出量↓o心率过慢（＜心率过慢（＜ 40次次/min）） 心率心率↓↓↓ SV↑ 每分输每分输出量出量↓o因此，一定范围内，HR增加，心输出量增加，HR最适宜时，心输出量最大。
lHR 的变化可以影响心肌的收缩能力的变化可以影响心肌的收缩能力ØHR 增快引起心肌收缩能力增强的现象，增快引起心肌收缩能力增强的现象，叫阶梯现象（叫阶梯现象（staircase phenomenonstaircase phenomenon）ØHRHR加快，胞内加快，胞内Ca2+Ca2+增高 The Affecting Factors of HRThe Affecting Factors of HRlNervous factors:üSympathetic nerve excitation can increase the HRüParasympathetic nerve excitation can decrease the HR;lHumoral factors:üNE,Adr, T3 ,T4 can increase the HR; p体温体温 体温升高体温升高1℃1℃，心率将增加，心率将增加12~18次次 小结：影响心输出量的因素：搏出量和心率•心室舒张期末容积：前负荷（回心血量和心室余血量决定），异长自身调节•动脉血压：后负荷，影响等容收缩期、射血期长短和射血速度•心肌收缩力：受ACh、NA及神经调节，主要影响心肌纤维张力、 收缩和舒张的速度。
•心率：40~180次/分钟 调节调节因因 素素心室前负荷心室前负荷(异长自身调节异长自身调节)心室后负荷心室后负荷（动脉血压）（动脉血压）心肌收缩能力心肌收缩能力（等长自身调节）（等长自身调节）定定 义义心心肌肌初初长长度度改改变变对对心心室室搏搏出量的影响出量的影响心室收缩射血过程心室收缩射血过程中所遇到的负荷对中所遇到的负荷对搏出量的影响搏出量的影响心肌收缩能力改变心肌收缩能力改变对心室搏出量的影对心室搏出量的影响表现表现形形 式式一一定定范范围围内内,心心舒舒末末期期容容积积增增大大，，初初长长度度增增加加，，收收缩加强，使博出量增加缩加强，使博出量增加一一定定范范围围内内血血压压升升高高，，心心输输出出量量不不下下降降血血压压过过高高心心输输出量减少出量减少心心肌肌收收缩缩能能力力增增强强，，搏搏出出量量增增加加；；心心肌肌收收缩缩能能力力减减弱弱，，搏搏出量减少出量减少调节调节机机 制制初初长长度度的的增增加加，，可可使使心心肌肌肌肌小小节节中中粗粗细细肌肌丝丝有有效效重重叠程度增加叠程度增加后后负负荷荷增增加加，，心心室室收收缩缩速速度度减减慢慢，，射射血血期期缩缩短短，，心心肌肌收收缩遇到阻力增大缩遇到阻力增大活活 化化 横横 桥桥 数数 多多 , ATP酶酶活活性性高高，，横横桥桥与与肌肌纤纤蛋蛋白白结结合合的的数数量量多多，，心心肌肌收收缩能力强缩能力强.影响影响因因 素素充盈时间长回心血多或剩充盈时间长回心血多或剩余血多心舒末期容积大。
余血多心舒末期容积大心肌伸展小静息张力大，心肌伸展小静息张力大，抵抗过度延伸抵抗过度延伸.心脏的负担加重，心脏的负担加重，长时间作用可致心长时间作用可致心肌肥厚、心室扩大肌肥厚、心室扩大交感神经兴奋，收交感神经兴奋，收缩能力增强缺缩能力增强缺02 、酸中毒心肌收缩、酸中毒心肌收缩能力下降能力下降。
