Signal Trasmission

Signal Transmission

At any signal transmission between neurons, there is the participation of the presynaptic neuron, which will send the information through the synaptic cleft, and the postsynaptic neuron that will receive this information.
Chemical messengers called neurotransmitters  carry the information form the presynaptic neuron to the postsynaptic neuron. They can also carry the signal from one neuron to an effector.
When the action potential reaches the end of the axon of the presynaptic neuron, it makes sacs that contain neurotransmitter -- synaptic vesicles -- to fuse with the membrane of the neuron. Then they release their neurotransmitter through exocytosis.
These neurotransmitter will reach the receptors of the postsynaptic neuron, which will start a action potential.
Neurotransmitter have either excitatory or inhibitory effect on the neuron. The difference is which channels they will open (excitatory will open the sodium gates, while inhibitory will open potassium gates.)
Acetylcholine is an example of excitatory neurotransmitter. It will cross the neuromuscular junction and will make the muscle contract. To breakdown the neurotransmitter, enzyme are necessary. That is the job for cholinesterase.