Binrdoaediisfaieatedsnd duce ISion of sidles with pepo montane ACh(ACh embrane Nerve ACh Ca termina Na K ACh Outside Muscle membrane Inside a
K 11 + Outside Inside Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ K + K + K + K + K + K + K K + + K + K + K + ACh ACh ACh Ca2+ induces fusion of vesicles with nerve terminal membrane. ACh is released and diffuses across synaptic cleft. ACh ACh binds to its receptor on the postsynaptic membrane Binding of ACh opens channel pore that is permeable to Na+ and K+ . Na+ Na+ K + Muscle membrane Ca2+ Ca2+
End plate potential(EPP,终板电位) The movement of nat and K depolarizes muscle membrane potential (EPP) o四oEo EPP o a Threshold Presynaptic terminal 90m Time(msec) Presynaptic AP Outside Muscle membrane Inside ACh Receptor Channels Voltage-gated Na channels Inward Rectifier K Channels
12 End Plate Potential (EPP，终板电位) Outside Inside Muscle membrane Presynaptic terminal Muscle Membrane Voltage (mV) Time (msec) -90 mV VK VNa 0 Threshold Presynaptic AP EPP The movement of Na+ and K+ depolarizes muscle membrane potential (EPP) ACh Receptor Channels Voltage-gated Na Channels Inward Rectifier K Channels
ACh Meanwhile ●● ACh ACh Nerve Chatfest港时hbes terminal ntc舵母ed into vesithecetate Acetate Outside Muscle membrane Inside
13 Meanwhile ... Outside Inside ACh ACh unbinds from its receptor Muscle membrane ACh so the channel closes ACh ACh ACh is hydrolyzed by AChE into Choline and acetate Choline Acetate Choline is taken up into nerve terminal Choline Choline resynthesized into ACh and repackaged into vesicle ACh
Structural Reality 0.5m A Muscle
14 Structural Reality
Neuromuscular transmission Properties of neuromuscular junction 1: 1 transmission An unidirectional process Has a time delay 20nm/0.5-1ms easily affect by drugs and some factors the nmj is a site of considerable clinica importance
15 Neuromuscular Transmission ➢ Properties of neuromuscular junction ➢ 1:1 transmission: ➢ An unidirectional process ➢ Has a time delay. 20nm/0.5-1ms ➢ easily affect by drugs and some factors ➢ The NMJ is a site of considerable clinical importance