萝卜家园Chapter2ExcitationandConductioofnervous

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1、 Chapter 2 Excitation and Conductio of nervous 神经的兴奋与传导神经的兴奋与传导 Metabolism 新陈代谢 Reproduction 生殖 Excitability 兴奋性Nervous tissue：nerve cells(neuron,神经元神经元)functional cells(功能细胞)neuroglia cells(神经胶质细胞神经胶质细胞).Support,nutrition,protection and isolation(绝缘).NF(nerve fiber):long tubercle of neuronaxon and

2、long dendrite.N(neuron):NF+connective tissue(结缔组织)Fig 2-2Section1 Irritability and Excitability应激性与兴奋性 1.Irritability应激性应激性 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(变形虫变形虫),sensitive plant(含羞含羞草草),tendential of pl

3、ant(植物的向植物的向性性)and silk tree(合欢合欢).condition:(1)sensibility for stimulus (2)signal conductibility (3)reaction of effecter Excitable cell:sensitive cell,nerve cell,muscle cellExcitability:irritability of excitable cells2.Excitability兴奋性兴奋性excitation兴奋兴奋：Reaction of vivo tissue and cell for stimulus活组

4、织或细胞对刺激发生的反应活组织或细胞对刺激发生的反应 transform变迁变迁 Stimulated cells generate action potential细胞受刺激时产生动作电位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活组织或细胞对刺激发生反应的能力的能力 transform(变迁)a kind of capacity that cell generate AP for stimulus细胞受刺

5、激时产生动作电位的能力细胞受刺激时产生动作电位的能力 transform(变迁)a kind of peculiarity that cellular membrane conductance is changed for stimulus 细胞受刺激时膜电导产生改变的特性细胞受刺激时膜电导产生改变的特性 Example:the sample of Sciatic nerve-gastrocnemius muscle (坐骨坐骨N-腓肠肌标本腓肠肌标本)Section 2 stimulation of causing excitation 引起兴奋的刺激 1.Def:It is a kind

6、of change of internal and external environment which can cause cell excitation 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(矩形波电刺激矩形波电刺激),co

7、ntrollable strength-duration(强度与时间可控强度与时间可控),little damage3.Essential factors of stimulus刺激的要素(1).intensity强度:Threshold intensity(阈强度阈强度)：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

8、threshold intensity.刺激持续时间和刺激持续时间和 强度强度-时间变化率固定时时间变化率固定时,引起组织兴奋所需的最小刺激强度。引起组织兴奋所需的最小刺激强度。Threshold stimulus(阈阈 刺刺 激激):It is a kind of stimulus that intensity is equal to threshold intensity.Subthreshold stimulus(阈下刺激阈下刺激)：It is a kind of stimulus that intensity is less than threshold intensity.Supra

9、liminal stimulus(阈上刺激阈上刺激)：It is a kind of stimulus that intensity is more than threshold intensity.Maximal intensity(顶强度顶强度):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(全或无全或无):For single cell,once threshold inten

10、sity 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)Duration The strength-duration curve of excited tissue 强度-时间曲线Fig 2-6 Rheobase(基强度基强度):the minimal threshold intensity.最小的阈强度Effective time(效用时间效用时间):(utilization time利用时).It is the shortest stimulative t

11、ime 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(强度的变化率强度的变化率)Fig 2-7Section 3 Index and Variation of excitability 兴奋性的指标和兴奋性的变化兴奋性的指标和兴奋性的变化1.Index of excitability兴奋性的指标兴奋性的指标(1).Rheobase and threshold intensity基强度与阈强度 excitability1/rheobase or threshold i

12、ntensity For example：A muscle B muscle threshold 0.7V 1.2V excitability stronger weaker2.Chronaxie时值时值Def:When the intensity 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/chronaxie3.changes of

13、 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 responseAbsolute refractory zero no response period绝对不应期绝对不应期Relative refractory lower than response for period相对不应期相对不应期 normal supraliminal stimulusSuperanormal a little higher response for period超常期超常期 than

14、 normal subthreshold stimulus Subnormal a little lower response for period低常期低常期 than normal supraliminal stimulus 1.Discovery 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 metalsFig2-13 Section 4 Bioelectricity phenomena生物电现象2.Rest

15、ing 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 injury 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 静息电位静息电位Def：The potential difference between two side

16、s of resting cellular membrane.静息状态下细胞膜两侧所存在的电位差Measure:microelectrode(微电极微电极)Extent:-50-100mvPolarization(极化极化):Under the resting condition,the membrane has polarity that interior is negative and exterior is positive内负外正(3)Action potential动作电位动作电位Def:a rapid,reversible and conductable changes of me

17、mbrane 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Produce and Conduction产生与传播:Fig 2-16Section5 Principle of Bioelectricity phenomena 生物电现象的产生原理Membrane theory:It was supposed by Bernstein in German in 1902For explaining RP.Ion theory:Supposed by Hodgkin and

18、Huxley in 1949 For explaining AP.Principle of Bioelectricity phenomena:It is bioelectricity 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

19、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 0.1molKCL 0.01mol EK =59.5log k+o/k+iK+-+1.RP and EKIons 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；extracellula

20、r:high concentration of Na+,negative ions are mainly Cl-胞外高钠，负离子以Cl-为主静息电位与EKThe 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(静息电位静息电位)的产生机制的产生机制：(1)静息状态下带电离子

21、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相当于EK2.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,

22、when it reaches threshold intensity,Na+entering 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机制机制1细胞受刺激时，膜缓慢去极化细胞受刺激时，膜缓慢去极化(depolarization)，膜，膜对钠的通透性增加，钠内流，达到阈

23、电位时，钠对钠的通透性增加，钠内流，达到阈电位时，钠内流内流 ，膜进一步去极化，膜电位与钠电导间形，膜进一步去极化，膜电位与钠电导间形成成Hodgkin cycle,钠快速内流形成钠快速内流形成AP的上升支，当的上升支，当趋近于趋近于ENa时，钠通道失活时，钠通道失活。Descending phase(下降支下降支)：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，钠通道关闭，钾通道开放，钾外流引起膜复极化钾外流引起膜复极化 Mechan

24、ism 2 of AP 动作电位动作电位的产生机制的产生机制 2图2-423.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

25、conductance=membrane permeability(2)I=V.G The characteristic of changes curve of GNa and GK voltage dependence,activated by depolarization,GNa was activated earlier.It was base of rising phase of AP,GK was activated later,it was base of descending phase of AP.电压依从性电压依从性,由去极化由去极化激活激活,GNa激活早是激活早是AP上升支

26、基础上升支基础;GK激活激活晚，是晚，是 AP下降支基础。下降支基础。电导及电导及AP GNa has inactivation but GK not.GNa有失活状态有失活状态而而GK没有此特性没有此特性5.Patch clamp experiment and single channel current 膜片钳实验和单通道离子电流膜片钳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

27、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 or open of channel is sudden when channel is open,they have stable conductance.opening time is different.special signals can control the ch

28、annels opening and closingSection 6 initiation and propagation of nerve impulse神经冲动的产生与传导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(兴奋的引起)(1)threshold potential and AP threshold potential(阈电位阈电位):it is the critical membrane potential value,which can cause AP.膜内负电位去极化到能引

29、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.Characteristics:细胞受刺激时膜电位的轻微去极细胞受刺激时膜电位的轻微去极化化it is increased by increasing of subthreshold stimulus intensity随阈下刺激增大而增大随阈下刺激增大而增大electrotonic s

30、pread电紧张性扩布电紧张性扩布summation phenomena（总和现象总和现象:时间性时间性、空、空间性间性）difference between local reaction and AP局部反应与局部反应与AP的区别的区别Local reaction APCaused by subthreshold stimulus Caused by supraliminal 阈下刺激引起阈下刺激引起 阈（上）刺激引起阈（上）刺激引起 A few of Na+channel Lots of Na+channel Graded response反应等级性反应等级性 “All or none”S

31、ummation effect总和效应总和效应 Not Decayed transmission Undecayed transmission 衰减性传播 非衰减性传播Myelinated NF(有髓鞘有髓鞘NF):saltory conduction(跳跃传导跳跃传导)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氏结间的局部电流Fig 2-502.Conduction velocity of nerve impulse神经冲动的传导速度 Conduction velocity

32、 NFs diameter Fig 2-22Classification of NF:A.Widest,myelinated(髓鞘)B.wider,myelinated C.thin,unmyelinated3.Characteristic of nerve impulse conductance at NF (NF上神经冲动传导的特点上神经冲动传导的特点)(1)isolation(绝缘性)(2)bidirectional conduction(双向传导双向传导)(3)undecayed(非衰减性)(4)relative untired(相对不疲劳性相对不疲劳性)(5)physiological intact(生理完整性生理完整性)1.enter“Chapter3 Transmission of excitationin nerve and muscle(兴奋在兴奋在神经肌肉间的传递神经肌肉间的传递)”2.back“introduction”3.over4.back to menu