Microsoft PowerPoint - MedElec106_Electrophysiology [相容模式]

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1 Electrophysiology ( 電生理學 ) Hsiao-Lung Chan Dept Electrical Engineering Chang Gung University chanhl@mail.cgu.edu.tw

2 Origin of biopotentials Na + Cl - Extracellular domain Phospholipid bilayer Intracellular domain K + 2

3 Simple equivalent circuit model of a cell membrane 3

4 Nernst potential (Ionic equilibrium potential) The Nernst equation 4

5 Nernst potential of a membrane premeable to one ion (e.g. K + ) drift K+ K+ K+ Outside (+) diffusion A - K+ d[ K ] J K ( diffusion) D dx J K+ K+ J K ( drift) Z[ K ] D: diffusion constant, Z: ion valence, [K + ]: ion concentration, μ: mobility, v & -dv/dx : voltage & electrical field across the membrane K J K ( diffusion) J K ( drift) d[ K D dx ] Z[ K ] Inside (-) At equilibrium, J K = 0, the Nernst equation is derived. 5 dv dx dv dx

6 Ion concentrations and Nernst potentials 6

7 Equivalent circuit model with ion channels 7

8 Patch clamp technique 8

9 Action potential ( 動作電位 ) 當細胞膜受到刺激而使得細胞電位產生隨時間變動的現象神經細胞受到刺激, 會將動作電位經由神經軸索 (axon) 傳遞下去心臟細胞運用動作電位的傳遞, 使得整個心臟可以同步收縮, 以最大的力量將血液送到全身各處 9

10 Action potential Na Outside cell Plasma membrane Inside cell Na Resting phase K + 3 Repolarizing phase K + Na + Na Depolarizing phase K + 4 Undershoot phase K + Membrane potential (mv) t 10

11 Action potential 11

12 All-or-none law ( 全有或全無定律 ) 全有如果刺激的強度和時間足夠大, 超過門檻值, 就可以引起一個完整而大小和持續時間固定的動作電位增大刺激的強度或時間並不會影響動作電位的大小或持續時間全無如果刺激的強度和時間沒超過門檻值, 就不會有動作電位產生 12

13 Refractory period ( 不反應期 ) 神經或肌肉細胞無法對刺激起反應的期間這發生於前一個刺激的反應尚在持續中或者剛結束的時候不反應期可再分為絕對不反應期 (absolute refractory period) 和相對不反應期 (relative refractory period) 在絕對不反應期, 神經細胞對所有的刺激都不會反應, 不管刺激的強度有多大相對不反應期則是對原來刺激的強度不反應, 只對強度更大的刺激有反應 13

14 Active channel: Sodium-potassium pump Remove 3 Na + for every 2 k + outside K+ Na+ inside K+ Na+ M. Bear et al, Neuroscience: exploring the brain, Lippincott Williams & Wilkins,

15 Nervous system Pages 11-13

16 Axon ( 軸突 ) to synapse ( 突觸 ) via neurotransmitter Pages 11-13

Brain Cerebrum ( 大腦 ) Receives and processes conscious sensation Generates thought, and controls conscious activity Hypothalamus ( 丘腦下部 ) controls most vegetative and endocrine functions,

17 Brain Cerebrum ( 大腦 ) Receives and processes conscious sensation Generates thought, and controls conscious activity Hypothalamus ( 丘腦下部 ) controls most vegetative and endocrine functions, including body temperature Medulla ( 延腦 ) Vital centers that regulates heart rate, respiratory rate, blood pressure, blood vessel, etc. Cerebellum ( 小腦 ) Controls motor activities and muscle contractions

18 Cerebral cortex ( 大腦皮質 ) 18

19 Cerebrum Gray matter refer to cerebral cortex ~ 25 mm thick but contains ~ 100 billion neurons Pyramidal neuron 19

20 Cerebral functional areas 20

21 21

22 Brain wave (electroencephalogram, EEG) 22

23 EEG rhythms (8 ~ 13 Hz) Alpha Beta Alpha (>13 ~ 30 Hz) (4 ~ <8 Hz) (<4 Hz) 23

24 EEG changes in sleep 24

25 Corticomuscular interaction Farina et al, J Appl Physiol,

26 Electromyogram (EMG) 26

27 EMG related to muscle contraction 27

28 Electroneurography (ENG) 測量末梢神經的傳導速度和對刺激起反應的潛伏時間神經傳導速度 (nerve conducion velocity, NCV) 影響神經傳導速度的主因 : (1) 神經纖維直徑越大, 傳導速度越大 (2) 有髓鞘的神經傳導速度比較大 (3) 健康正常的神經通常比受傷的神經傳導快 28

29 Conduction velocity of motor nerve 29

30 Conduction velocity of sensory nerve 30

31 Control of cardia pacing by autonomic nervous system 31

32 Cardiac conduction system 32

33 Cardiac conduction system 33

34 Luo-Rudy cardia cell model 34

35 A period of plateau Electrical equilibrium by Ca 2+ inflow and K + outflow Na + channel open Release Ca 2+ from JSR [Ca] in cytoplasm Recollect Ca 2+ into NSR 35

36 Waveforms of action potentials 36

37 Electrocardiogram (ECG) 37

38 P wave : Atrial depolarization QRS complex : Ventricular depolarization T wave : Ventricular repolarization U wave : Slow repolarization of ventricular muscle R-R : Heart period P-R : Conduction delay in the AV-node Q-T, S-T : Ventricular repolarization time 38

39 Retina electrophysiology Peter Dayan and L.F., Theoretical Neuroscience, MIT Press,

40 Absorption rate of rod and cone cells 40

41 Electromagnetic spectrum 41

42 Flash response of rod and cone cells 42

43 Electrorectinogram (ERG) 43

44 Retinal Prosthesis implant system Wentai Liu et al 44

45 Multiple-unit Artificial Retinal Chipset (MARC) 45

46 Implanted MARC 46

47 Reference 中華民國生物醫學工程學會, 生物醫學工程導論,2008 年, 滄海圖書 G. D. Baura, Medical device technologies, Elsevier Inc.,

绪言

绪论生理学 (physiology) 是生物学的一个分支, 它以生物机体的功能 (function) 为研究对象, 是研究生物体的正常生命活动规律的科学动物生理学 (animal physiology) 是生理学的一个分支, 研究动物体的整体及其各个系统的器官