7 Steps at Neuromuscular Junction

Two ways ACh is removed from synaptic cleft

1. ACh diffuses away from the synapse 2. The enzyme Acetylcholinesterase (AChE) quickly removes ACh from synaptic cleft, breaks it down, into acetic acid and choline; choline is then transported back into the axon terminal for use in synthesizing ACh.

Step 4

Acetylcholine (ACh) diffuses across the synaptic cleft and binds to ACh receptors which contain ligand-gated cation channels.

Step 1

Action potential travels the length of a motor neuron to the axon terminal.

Step 3

Calcium ion entry cause synaptic vesicles to release the neurotransmitter Acetylcholine (ACH) via exocytosis.

Step 5

Ligand-gated cation channels open.

ACh is removed from the synaptic cleft.

Neurotransmission to a muscle fiber ceases

Step 7

Once membrane potential reaches a threshold value, an action potential propagates along the sarcolemma.

Step 6

Sodium ions enter the muscle fiber, while potassium ions exit the muscle fiber. The greater influx of sodium ions, relative to the outflux of potassium ions, causes the membrane potential to become less negative.

Step 2

Voltage-gated calcium channels open, allowing calcium ions to diffuse into the axon terminal.