Question

Each presynaptic terminal contains ___________, which contain the neurotransmitter __________ that, when released, cause ligand-gated Na+ channels to open in the motor end-plate. This causes __________ in the muscle cell.

Answer 1

The correct answers are: Neurotransmitter Vesicles, Acetylcholine, Contraction.

Step-by-step explanation:

• At the neuro-muscular junction, impulses are transmitted in the following manner:

1. The impulse is carried by an action potential (variable opening and closing of different ion channels located on the membrane of the neurons allowing variable ion movement) to the neuron at the neuro-muscular junction.
2. The action potential causes the opening of the voltage dependent calcium channels in the axon terminal of the neuron allowing the entry of calcium ions.
3. This causes the neurotransmitter vesicles containing the neurotransmitter acetylcholine to fuse with the pre-synaptic membrane.
4. Acetylcholine is released by the method of exocytosis into the synaptic cleft.
5. The acetylcholine molecules bind to the the cognate receptors present in the membrane of the muscle cell (sarcolemma).
6. This causes the flow of sodium ions into and potassium ions out of the muscle cell, which generates action potential in the muscle cell.
7. This action potential causes the muscle cell to contract.