7-Synatic Transmission 1 Figs BW

Exocytosis is seen at right where the vesicle in

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Unformatted text preview: right where the vesicle in middle of terminal fuses with membrane. this synaptic vesicle completely fuses with and collapse into membrane. as more and more vesicle collapse their membrane into synaptic membrane, this vesicle membrane push off the side. At some place away from release site, the vesicle membrane is retrieve but stay intact and reform back into synaptic vesicles and refill 4. newly discover mechanism (occur at synapse) where vesicle keep very close to presynaptic terminal, where it fuse with membrane and do not completely collapse. instead it form a fusion-pore, and allow neurotransmitter to rapidly diffuse out. At either 3 or 4 neurotransmitter, as soon as vesicle collapse or pore is form, diffuse out to extracellular solution because there's such a high concentration inside cell. kiss and run mechanism: the vesicle never lose this integrity. once it's empty, it pulls away from terminal, is recycle and refilled. step 4 is diffusion of transmitter across narrow space between pre and post synaptic membrane, called synaptic cleft (see next slide) vesicle collapse and retrieval fusion-pore kiss and run Steps in Chemical Synaptic Transmission here at step 4: this is the rapid diffusion of neurotransmitter through narrow synaptic cleft (very 10th of nm, very short distance). on post-synaptic membrane, there are receptors shown in pink for neurotransmitter.there are 2 types of receptor: 1. if the neurotransmitter bind to receptor and there's a change in ion channel (the receptor is a ion channel or it's couple with an ion channel). this receptor is ionotropic receptor. the effect can be opening or closing in ion channel and the resulting changes in ionic fluxes across the membrane and depolarization or hyperpolarization of postsynaptic cell 2. if the neurotransmitter bind to receptor and trigger metabolic changes,, through second messenger system. metabotropic. hormone can exert on cell through neurotransmitter when they bind to metabotropic receptors. Presynaptic Terminal 3 2 t...
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