《萝卜家园Chapter2ExcitationandConductioofnervous.ppt》由会员分享，可在线阅读，更多相关《萝卜家园Chapter2ExcitationandConductioofnervous.ppt（47页珍藏版）》请在三一文库上搜索。
1、Chapter 2 Excitation and Conductio of nervous 神经的兴奋与传导,Metabolism 新陈代谢 Reproduction 生殖 Excitability 兴奋性,Nervous tissue ： nerve cells (neuron,神经元) functional cells(功能细胞) neuroglia cells(神经胶质细胞). Support, nutrition, protection and isolation(绝缘).,NF (nerve fiber): long tubercle of neuron axon and long
2、dendrite. N (neuron): NF + connective tissue(结缔组织) Fig 2-2,Section1 Irritability and Excitability 应激性与兴奋性,1. Irritability应激性 Def : It is a kind of capacity that the vivo tissue and cells generate reaction for stimulus. 活的机体、组织、细胞对刺激 发生反应的能力 Example: amoeba(变形虫), sensitive plant(含羞草), tendential of p
3、lant(植物的向性)and silk tree(合欢).,condition: (1) sensibility for stimulus (2) signal conductibility (3) reaction of effecter Excitable cell: sensitive cell, nerve cell, muscle cell Excitability: irritability of excitable cells,2. Excitability兴奋性,excitation兴奋： Reaction of vivo tissue and cell for stimulu
4、s活组织或细胞对刺激发生的反应 transform变迁 Stimulated cells generate action potential细胞受刺激时产生动作电位,Excitability ： a kind of capacity that vivo tissue and cell generate reaction for stimulus.活组织或细胞对刺激发生反应的能力 transform(变迁) a kind of capacity that cell generate AP for stimulus细胞受刺激时产生动作电位的能力,transform(变迁) a kind of pe
5、culiarity that cellular membrane conductance is changed for stimulus 细胞受刺激时膜电导产生改变的特性,Example : the sample of Sciatic nerve-gastrocnemius muscle (坐骨N-腓肠肌标本),Section 2 stimulation of causing excitation 引起兴奋的刺激,1. Def : It is a kind of change of internal and external environment which can cause cell e
6、xcitation 能引起细胞兴奋的内外环境条件的变化,2.Quality and Classification性质与种类 Quality: mechanical stimulus, chemical stimulus, temperature stimulus, electrical stimulus ect. electrical stimulus: the electrical stimulus of rectanglar waves(矩形波电刺激), controllable strength-duration(强度与时间可控), little damage 3. Essential
7、factors of stimulus刺激的要素 (1). intensity强度:,Threshold intensity(阈强度)：When stimulus duration and rate of change is stable, tissue can generate excitation by a minimal intensity of stimulus, the minimal intensity of stimulus is called threshold intensity .刺激持续时间和 强度-时间变化率固定时,引起组织兴奋所需的最小刺激强度。 Threshold
8、stimulus(阈 刺 激): It is a kind of stimulus that intensity is equal to threshold intensity. Subthreshold stimulus(阈下刺激)： It is a kind of stimulus that intensity is less than threshold intensity.,Supraliminal stimulus(阈上刺激)： It is a kind of stimulus that intensity is more than threshold intensity. Maxi
9、mal intensity(顶强度): It is the minimal intensity of stimulus which can cause muscle to do the most contraction reaction.引起肌肉做最大收缩反应的最小刺激强度。 All or none(全或无): For single cell, once threshold intensity is reached, the cell will generate the maximal reaction. 对单个细胞来说,一旦刺激强度达到阈值,就会引起这个细胞作最大反应。,(2)Duratio
10、n The strength-duration curve of excited tissue 强度-时间曲线 Fig 2-6 Rheobase(基强度): the minimal threshold intensity. 最小的阈强度 Effective time(效用时间): (utilization time利用时). It is the shortest stimulative time which can excite tissue by stimulus of rheobase. 用基强度刺激,引起兴奋所需要的最短刺激时间,(3). Rate of change(强度的变化率) F
11、ig 2-7,Section 3 Index and Variation of excitability 兴奋性的指标和兴奋性的变化,1.Index of excitability兴奋性的指标 (1). Rheobase and threshold intensity 基强度与阈强度,excitability1/rheobase or threshold intensity For example： A muscle B muscle threshold 0.7V 1.2V excitability stronger weaker,2. Chronaxie时值 Def : When the i
12、ntensity of stimulus is twice as rheobase, the shortest duration of stimulus ,which can excite tissue, is called chronaxie.当刺激强度为基强度的二倍时,引起兴奋所需的最短刺激作用时间,excitability1/ chronaxie,3. changes of excitability during action potential and resumption (组织兴奋及其恢复过程中兴奋性的变化),phases excitability response Absolut
13、e refractory zero no response period绝对不应期 Relative refractory lower than response for period相对不应期 normal supraliminal stimulus Superanormal a little higher response for period超常期 than normal subthreshold stimulus Subnormal a little lower response for period低常期 than normal supraliminal stimulus,1. Di
14、scovery of bioelectricity生物电的发现 电鳗numbfish 伽发利Galvani (17371798） 动物电 animal electricity 伏特volt 双金属电流 A current by two kind of metals Fig2-13,Section 4 Bioelectricity phenomena 生物电现象,2. Resting potential and action potential 静息电位与动作电位 (1) Injury potential损伤电位 Def : The potential difference between in
15、jury site and intact site of tissue. 组织的损伤部位与完整部位之间的电位差 Essence: the potential difference of two sides of membrane. 膜两侧的电位差,(2) Resting potential 静息电位 Def ：The potential difference between two sides of resting cellular membrane. 静息状态下细胞膜两侧所存在的电位差 Measure: microelectrode(微电极) Extent: -50- -100mv Pola
16、rization(极化): Under the resting condition, the membrane has polarity that interior is negative and exterior is positive内负外正,(3) Action potential动作电位 Def: a rapid, reversible and conductable changes of membrane potential in stimulated cell on the base of RP. 细胞膜受到刺激后在原有RP基础上发生的一次膜两侧电位的快速而可逆的倒转与复原 Pro
17、duce and Conduction产生与传播: Fig 2-16,Section5 Principle of Bioelectricity phenomena 生物电现象的产生原理,Membrane theory : It was supposed by Bernstein in German in 1902 For explaining RP. Ion theory : Supposed by Hodgkin and Huxley in 1949 For explaining AP.,Principle of Bioelectricity phenomena: It is bioelec
18、tricity phenomena that is caused by unbalanced distribution of charged ions in two sides of membrane and change of permeability of the ions under different condition . 生物电产生的基本原理：细胞生物电现象的各种表现，主要是由于某些带电离子在细胞膜两侧不均衡分布，以及膜在不同情况下对这些离子的通透性发生改变所造成。,Transmembrane diffusion of charged ions 带电离子的跨膜扩散,KCL 0.1m
19、ol,KCL 0.01mol,EK = 59.5log k+ o/k+i,K+,- -,+ +,1. RP and EK,Ions distribution in two sides of membrane: Intracellular: high concentration of K+ , many negative ions formed by organic molecules; 胞内高钾，具较多的由有机分子形成的负离子； extracellular : high concentration of Na+ , negative ions are mainly Cl- 胞外高钠，负离子以C
20、l-为主,静息电位与EK,The principle of RP： (1)Unbalanceable distribution of charged ions in two sides of membrane. (2)High membrane permeability for K + (3)RP is caused by outward diffusion of K +, RP is equal to EK. RP(静息电位)的产生机制： (1)静息状态下带电离子在膜两侧呈不均衡分布； (2)静息状态下膜的通透性主要表现为钾的通透性； (3)RP的产生主要是由于钾离子的外向扩散造成，RP相当
21、于EK,2. AP and changes of membrane permeability 动作电位与膜的通透性变化,proof ： relationship between Na+ and AP Fig 2-29,Mechanism 1 of AP：,when membrane is depolarized slowly by stimulating, the membranes permeability is increased for Na+, Na+ flow into cell, when it reaches threshold intensity , Na+ entering
22、is accelerated,depolarization is enhanced, membrane potential and Na conductance generate Hodgkin cycle. Na+ rapid entering forms rising phase ,when tend to ENa, Na+ channel is inactivated.,AP机制1,细胞受刺激时，膜缓慢去极化(depolarization)，膜对钠的通透性增加，钠内流，达到阈电位时，钠内流 ，膜进一步去极化，膜电位与钠电导间形成Hodgkin cycle, 钠快速内流形成AP的上升支，当
23、趋近于ENa时，钠通道失活。,Descending phase(下降支)：Na+ channels are closed and K+ channels are opened. K+ flow to out of cell, membrane repolarizes钠通道关闭，钾通道开放，钾外流引起膜复极化,Mechanism 2 of AP 动作电位的产生机制 2,图2-42,3. Na-K pumps active transport 钠钾泵的主动转运,Keeping polarization： (1)Entering of positive ions Entering of Na+ 静息
24、状态下钾外流 大于钠内流； (3)Impermeability of many intracellular organic negative ions 胞内有大量 不能通透的有机负离子。,4. Classic voltage clamp experiment 经典的电压钳实验,Design basis : (1) membrane conductance = membrane permeability (2) I=V.G,The characteristic of changes curve of GNa and GK, voltage dependence, activated by dep
25、olarization, GNa was activated earlier. It was base of rising phase of AP, GK was activated later, it was base of descending phase of AP. 电压依从性,由去极化 激活,GNa激活早是 AP上升支基础;GK激活 晚，是 AP下降支基础。,电导及AP, GNa has inactivation but GK not. GNa有失活状态 而GK没有此特性,5. Patch clamp experiment and single channel current 膜片钳
26、实验和单通道离子电流,细胞是通过细胞膜与外界隔离的，在细胞膜上有很多通道，细胞就是通过这些通道与外界进行物质交换的。这些通道由单个分子或多个分子组成，允许一些离子通过。通道的调节影响到细胞的生命和功能。 内尔和萨克曼合作，结果发现当离子通过细胞膜上的离子通道的时候，产生十分微弱的电流。内尔和萨克曼在实验中， 证实了离子通道是存在的，以及它们如何发挥功能的。有一些离子通道上有感应器，他们甚至发现了这些感应器在通道分子中的定位。,patch clamp experiment,Na+ current,Channel characteristics ：,Fig 2-37 , 2-36, close o
27、r open of channel is sudden when channel is open, they have stable conductance. opening time is different. special signals can control the channels opening and closing,Section 6 initiation and propagation of nerve impulse 神经冲动的产生与传导,1.initiation of nerve impulse (initiation of excitation) 神经冲动的产生(兴奋
28、的引起) (1) threshold potential and AP threshold potential (阈电位) : it is the critical membrane potential value,which can cause AP. 膜内负电位去极化到能引起 动作电位产生的临界膜电位数值,(2) local excitation and its characteristic 局部兴奋及其特性,Local excitation ：When cell is stimulated, its membrane potential is slightly depolarized.
29、Characteristics:细胞受刺激时膜电位的轻微去极化 it is increased by increasing of subthreshold stimulus intensity随阈下刺激增大而增大 electrotonic spread电紧张性扩布 summation phenomena（ 总和现象:时间性、空间性 ）,difference between local reaction and AP 局部反应与AP的区别,Local reaction AP Caused by subthreshold stimulus Caused by supraliminal 阈下刺激引起
30、 阈（上）刺激引起 A few of Na+ channel Lots of Na+ channel Graded response反应等级性 “All or none ” Summation effect总和效应 Not Decayed transmission Undecayed transmission 衰减性传播 非衰减性传播,Myelinated NF(有髓鞘NF): saltory conduction (跳跃传导) Local circuit current of node of Ranvier (朗飞氏结) of excited and unexcited已兴奋的与未兴奋的朗飞
31、氏结间的局部电流 Fig 2-50,2.Conduction velocity of nerve impulse 神经冲动的传导速度 Conduction velocity NFs diameter Fig 2-22 Classification of NF: A. Widest,myelinated(髓鞘) B. wider,myelinated C. thin,unmyelinated,3.Characteristic of nerve impulse conductance at NF ( NF上神经冲动传导的特点),(1)isolation(绝缘性) (2)bidirectional conduction(双向传导) (3)undecayed(非衰减性) (4)relative untired(相对不疲劳性) (5)physiological intact(生理完整性),1.enter“Chapter3 Transmission of excitationin nerve and muscle (兴奋在神经肌肉间的传递)” 2.back“introduction” 3.over 4.back to menu,