生理学——细胞的生物电现象PPT精选文档

1、Biological electric activity of the cell恩格斯 恩格斯在100多年前总结自然科学成就时指出：“地球几乎没有一种变化发生而不同时显示出电的现象”。 Recording biological activitymV0-70mV0-70+transmembrane resting potentialresting potentialmembrane potential-100+200-20-40-60-80mV阈电位阈电位离子浓度（ mmol/L ）主要离子膜内膜外膜内与膜外离子比例膜对离子通透性N Na a+ 101:10通透性很小K

2、 K+ +1551554 439:139:1通透性大ClCl- -4 41201201:301:30通透性次之A A- -155155无通透性Origin of biological electricity K+ equilibrium potential, EKKClKClsuppose：1. Solution: KCl2. Permeable to K+ only K+Cl-Ek= lnRTZFK+outK+inR: gas constantT : absolute temperatureZ: valanceF: Faraday C.Nernst formulainoutinoutNote

3、: net diffusion of K+ equals zero.Ek= LnRTZFK+outK+ininoutsuppose：1. Solution: KCl2. Permeable to K+ only Nernst formulaK+Cl-Discussing:1.Do K+ permeability influence EK ?2. If the solution contains Na+, how about EK ?Ek= lnRTZFK+outK+ininoutElectrochemical driving force for K+: EM - E K suppose：1.

4、Solution: KCl2. Permeable to K+ only Nernst formulaK+Cl-计算值实测值实测值计算值Summary EK: EK in such a condition that the net movement of K+ across membrane is zero. Resting potential: Em maintains constant when the charge movement of all kinds of ion across the membrane is zero. The higher the K+ relative pe

5、rmeability is, the Closer to EK the RP is. Na +-K +pump maintains Na+ and K+ concentration gradients across membrane and diffusion force.二、动作电位的产生机制 Formation mechanism of action potential 动作电位的产生机制Formation mechanism of action potential1.电化学驱动力 Electrochemical driving force驱动力膜电位平衡电位EmENa7060130mVE

6、mEk70(90)+20mVEmECl70(70)070mVNa+Ca2+K+Cl-Na+70mV02.动作电位期间膜电导的变化INa= GNa (EmENa)膜电导=膜对离子的通透性Voltage clampNa+K+3.膜电导变化的机制是离子通道的活动Neher Sakmann 宏膜电流macroscopial current I=iP0NThe mechanism in production and propagation of action potential+阳极:内向电流 超极化 兴奋性阴极:外向电流 去极化 兴奋性-70mV-55-85threshold potentialEle

7、ctrotonic propagationS1S2Spatial summationS1S2Temporal summation1. 无髓神经纤维-“局部电流学说” local current theory静息部位膜内为负电位，膜外为正电位兴奋部位膜内为正电位，膜外为负电位在兴奋部位和静息部位之间存在着电位差膜外的正电荷由静息部位向兴奋部位移动膜内的正电荷由兴奋部位向静息部位移动形成局部电流膜内：兴奋部位相邻的静息部位的电位上升膜外：兴奋部位相邻的静息部位的电位下降去极化达到阈电位，触发邻近静息部位膜爆发新的AP局部电流：跳跃式传导(saltatory conduction 施旺细胞Schwanns cell 朗飞结Node of RanvierIiImrirmThe local-circuit current and propagation of AP along the cell membrane : rm/ri=rm ri Cm组织兴奋性（Excitability of tissue）hm备用状态激活状态失活状态 备用状态 小结Brief Summary一、试述细胞在兴奋及恢复过程中 兴奋性变化的