BIO SCI E109 Chapter Notes - Chapter 7: Electrical Synapse, Cardiac Muscle, Neurotransmitter
1 Oct 2016
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Course: e109 presynaptic neuron: the neuron sending the signal. A synapse may be electrical or chemical: electrical synapses involve gap junctions. At an electrical synapse, action potentials conduct directly between adjacent cells through gap junctions. Gap junction contains tubular connexons , which function as tunnels. Common in cardiac muscle and visceral smooth muscle. Advantage: faster & synchronization (heartbeat/gastrointestinal tract: chemical synapses involve the release of neurotransmitter into a synaptic cleft. Synaptic delay: the time required for these processes at a chemical synapse. =0. 5msec. [1] action potential arrives at a synaptic end bulb of a presynaptic axon. Increased ca2+ concentration triggers exocytosis of the synaptic vesicles. [3] ca2+ binds to synaptotagmin (in the membrane of the synaptic vesicle) synaptotagmin bind to the snare proteins fusion of synaptic vesicle with presynaptic membrane neurotransmitter are released into the synaptic cleft. [synaptobrevin in v-snare, syntaxin and snap-
