Give two reasons why transmission across a cholinergic synapse is unidirectional.

1

2

Figure 4 shows the changes in membrane potential in a postsynaptic neurone after repeated stimulation from a single presynaptic neurone.

Name and explain the type of summation shown in Figure 4.

Suggest and explain how MG can weaken contraction of muscles.

Do not include details of myofibril or muscle contraction in your answer.

Mestinon can help in the treatment of MG. Explain how.