9.心动周期及心脏泵功能调节.ppt

Ventricular function curve (Frank-Starling curve) Factors affecting preload (EDV) (1) Venous return Filling time Venous return rate Compliance (2) Residual blood in ventricles after ejection 2. Afterload（后负荷）(Usually measured as arterial pressure) Afterload has very little effect on the normal ventricle However, as systolic failure develops even small increases in afterload have significant effects on compromised ventricular systolic function Conversely, small reductions in afterload in a failing ventricle can have significant beneficial effects on impaired contractility Congestive heart failure (CHF) 3. Myocardial contractility (Inotropic state) （心肌收缩性[变力状态]） Homometric regulation （等长调节） To further increase the stroke volume: fill it more fully with blood AND deliver sympathetic signals (norepinephrine and epinephrine); it will also relax more rapidly, allowing more time to refill. Sympathetic signals (norepinephrine and epinephrine) cause a stronger and more rapid contraction and a more rapid relaxation. Factors regulating contractility HR??CO? (CO = SV x HR) HR??Contractility? (Treppe effect) HR?? diastolic filling time ? Regulation of heart rate 40~180 /min，HR??CO? >180 /min，or <40/min，CO? Control of heart rate To speed up the heart rate: deliver the sympathetic hormone, epinephrine, and/or release more sympathetic neurotransmitter (norepinephrine), and/or reduce release of parasympathetic neurotransmitter (acetylcholine). T, ions, metabolites, other hormones Staircase phenomenon (Treppe effect , Force-frequency relationship) Increase in rate of contraction (heart rate) causes increase in contractility To increase SV, increase:end-diastolic volume,norepinephrine delivery from sympathetic neurons, and epinephrine delivery from the adrenal medulla. To increase HR, increase: norepinephrine delivery from sympathetic neurons, and epinephrine delivery from adrenal medulla (reduce parasympathetic). It is not possible, under normal circumstances, t