Describe the series of events from the arrival of an action potential at the pre-synaptic membrane of a cholinergic synapse to the generation of a new action potential at the post synaptic membrane?

1. An action potential arriving at the pre-synaptic membrane stimulates voltage-gated calcium channels to open and calcium ions diffuse into the neuron through these calcium channels.

2. Influx of calcium causes synaptic vesicles to fuse with the pre-synaptic membrane.

3. When these vesicles fuse with the pre-synaptic membrane they release acetylcholine neurotransmitter into the synaptic cleft.

4. Acetylcholine diffuses across the synaptic cleft and binds to cholinergic receptors on the post-synaptic membrane

5. This causes sodium ion channels in the post-synaptic membrane to open and thus the influx of sodium into the membrane triggers a new action potential to be generated at the post-synaptic membrane.

NB/ ** Resting potential of a cell, the outside of the cell is more positive than the inside so when sodium channels are opened, Na+ move along the electrochemical gradient from outside the cell into the cell, making the inside of the cell less negative (more positive). If the potential difference (difference in charge between the outside and inside of the cell) reaches a threshold, an action potential is triggered.