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Bio 220 Lecture 17: Neurobiology III Campbell, 5th, 971-975, bottom 977-979 Exam (Friday) includes lecture material through the nervous system, neuro simulation and material covered in neurohistology handout from lab. I. Connections between neurons (continued) Today, we'll concentrate on chemical synapses

A. Chemical Synapse

48.10

Synapses are specialized regions of the two cells that are brought within 10- 40 nm, but not connected. The axon terminal contains vesicles filled with chemical messenger (neurotransmitter).

Presynaptic cell

Postsynaptic cell

1. Neurotransmitter release When the action potential arrives at the axon terminus, it causes voltage- gated calcium channelsto open. The influx of Ca++ ionscauses the neurotransmitter-containing vesicles to fusewith the plasma membrane, releasing their contents into the synaptic cleft.