生理學(xué)——細(xì)胞的生物電現(xiàn)象PPT精選文檔

1、Biological electric activity of the cell恩格斯 恩格斯在100多年前總結(jié)自然科學(xué)成就時(shí)指出：“地球幾乎沒有一種變化發(fā)生而不同時(shí)顯示出電的現(xiàn)象”。 Recording biological activitymV0-70mV0-70+transmembrane resting potentialresting potentialmembrane potential-100+200-20-40-60-80mV閾電位閾電位離子濃度（ mmol/L ）主要離子膜內(nèi)膜外膜內(nèi)與膜外離子比例膜對離子通透性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無通透性O(shè)rigin 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-計(jì)算值實(shí)測值實(shí)測值計(jì)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、動(dòng)作電位的產(chǎn)生機(jī)制 Formation mechanism of action potential 動(dòng)作電位的產(chǎn)生機(jī)制Formation mechanism of action potential1.電化學(xué)驅(qū)動(dòng)力 Electrochemical driving force驅(qū)動(dòng)力膜電位平衡電位EmENa7060130mVE

6、mEk70(90)+20mVEmECl70(70)070mVNa+Ca2+K+Cl-Na+70mV02.動(dòng)作電位期間膜電導(dǎo)的變化INa= GNa (EmENa)膜電導(dǎo)=膜對離子的通透性Voltage clampNa+K+3.膜電導(dǎo)變化的機(jī)制是離子通道的活動(dòng)Neher Sakmann 宏膜電流macroscopial current I=iP0NThe mechanism in production and propagation of action potential+陽極:內(nèi)向電流 超極化 興奮性陰極:外向電流 去極化 興奮性-70mV-55-85threshold potentialEle

7、ctrotonic propagationS1S2Spatial summationS1S2Temporal summation1. 無髓神經(jīng)纖維-“局部電流學(xué)說” local current theory靜息部位膜內(nèi)為負(fù)電位，膜外為正電位興奮部位膜內(nèi)為正電位，膜外為負(fù)電位在興奮部位和靜息部位之間存在著電位差膜外的正電荷由靜息部位向興奮部位移動(dòng)膜內(nèi)的正電荷由興奮部位向靜息部位移動(dòng)形成局部電流膜內(nèi)：興奮部位相鄰的靜息部位的電位上升膜外：興奮部位相鄰的靜息部位的電位下降去極化達(dá)到閾電位，觸發(fā)鄰近靜息部位膜爆發(fā)新的AP局部電流：跳躍式傳導(dǎo)(saltatory conduction 施旺細(xì)胞Schwanns cell 朗飛結(jié)Node of RanvierIiImrirmThe local-circuit current and propagation of AP along the cell membrane : rm/ri=rm ri Cm組織興奮性（Excitability of tissue）hm備用狀態(tài)激活狀態(tài)失活狀態(tài) 備用狀態(tài) 小結(jié)Brief Summary一、試述細(xì)胞在興奮及恢復(fù)過程中 興奮性變化的