In: Biology
Identify the type of electrical events that occur at the axon and at the dendrite and describe a characteristic feature of each.
• Chemicals known as neurotransmitters are stored in membrane-bound vesicles at the axon terminal of neurons
Membrane proteins on the vesicle bind membrane proteins at the axon terminal to tether the vesicles in place.
A protein known as complexin acts like a brake, and stop the vesicles from fusing into the membrane and releasing their contents (remember: complexin complicates the process of vesicle fusion)
The vesicle protein synaptotagmin can bind and release complexin in the presence of calcium
As the action potential travels down the axon, positive ions continue to flood the cell. Eventually, this influx reaches the very end of the neuron – the axon terminal. When this happens, the positive ions trigger voltage-gated calcium channels to open and let calcium ions into the cell. The calcium ions can then activate synaptotagmin to release the brake, and the vesicles fuse with the cell membrane, and the vesicle contents are released into the synaptic cleft.