The nervous system is a combination of electrical and chemical synapses; this slows transmission but has numerous benefits.
Sequence of Events
Step 1
Chemical Synthesis of neurotransmitters (small ones - in axon terminals; neuropeptides - in cell body)
Step 2
At the presynaptic terminal, action potential opens Ca voltage gated channels; Ca then causes neurotransmitters to be released into the synaptic cleft.
Step 3
The molecules diffuse across cleft, attach to receptors, and alter the activity of the postsynaptic neuron.
Step 4
The neurotransmitter molecules separate from their receptors
Step 5
Reuptake into presynaptic cell or diffusion of neurotransmitter
Effect on Postsynaptic Cell
Ionotropic effect (quick and short effect): ligand-gated channel opens. Ex. glutamate: causes EPSP, while GABA opens Cl gates, causing IPSP. Ex. For vision/hearing.
Metabotropic Effect (slower but longer lasting effect): releases G protein that causes chain reaction. Ex. for taste, smell, pain.
Step 6
Some postsynaptic cells send reverse messages to control further release of neurotransmitters
Synapses
Synapses are the building blocks of behavior. Ex. ppl w greater amounts of dopamine are more impulsive and inclined to seek immediate pleasure