BIOL 201 Lecture Notes - Lecture 36: Axon Terminal, Exocytosis, Motor Neuron
27 Nov 2015
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Want the space to be as small as possible because diffusion is unreliable. As the action potential propagates into the axon terminal and it gets depolarized, calcium channels are opening. They change their conformation in response to the membrane potential, allowing a local influx of calcium which triggers exocytosis. Binding of neurotransmitter causes depolarization of the target cell. Neurotransmitter will diffuse out of synaptic cleft and bind to a receptor, e. g. ach. Causes voltage-gated channels to open (e. g. na) which will depolarize the cell at the site where the motor neuron is contacting it. This opens adjacent voltage-gated sodium channels so more na flows in. This leads to the opening of a calcium-release channel. Will open an ion channel in response. The acetylcholine receptor is a ligand-gated ion channel. Neurotransmitters are packaged into synaptic vesicles by h+ gradients. V-class proton pump will use the energy of atp hydrolysis to pump protons into the synaptic vesicle.
