8 3. Bioelectrical phenomena of the cell e Several basic concepts 米 Excitability *k Excitable cells or tissues k Stimulus excitation ck Threshold stimulus, intensity or threshold k Relationship between Excitability threshold o Bioelectrical phenomena of nerve muscle cells k resting potential(rp) k Action potential (AP)
§ 3. Bioelectrical phenomena of the cell • Several basic concepts * Excitability * Excitable cells or tissues * Stimulus & excitation * Threshold stimulus, intensity or threshold * Relationship between Excitability & threshold • Bioelectrical phenomena of nerve & muscle cells * Resting potential (RP) * Action potential (AP)
ek Resting potential (rp) A constant potential difference at rest Between both sides of the membrane Negative inside relative to outside 70 mv(neuron),-90 mv(muscle) k Action potential (AP) Occurs when a stimulus is applied a brief deflection(spike) of the baseline Depolarization repolarization phases All or none not attenuated propagation
* Resting potential (RP) A constant potential difference at rest Between both sides of the membrane Negative inside relative to outside −70 mV (neuron), −90 mV (muscle) * Action potential (AP) Occurs when a stimulus is applied A brief deflection (spike) of the baseline Depolarization & repolarization phases All or none & not attenuated propagation
锋电位 负后电位 电位变化 正后电位 Relationship 超常期 兴奋性 between excitation 不应期(相对和绝对不应期)低常期 时间(ms) AP
Relationship between excitation & AP
放大器 放大器 示波器 ++千占++++++ +++口++++++\示波器 细 胞 细 ++++++++++ +++++++++ (1)电极A与B均置于细胞外表面 (2)电极B插人细胞内,电极A置于细胞膜外表 面,细胞膜呈现外正内负的极化状态 图2-4证明静息电位存在的实验示意图 Measurement of resting potential (rP)
Measurement of resting potential (RP)
膜电位(mV) +35 0 锋电位 國电位 负后电位 55 正后电位 70 Action 时间(m) potential
Action potential