Explain why nerve impulses can only travel in one direction across a chemical synapse.
Figure 1 shows the changes in membrane potential in a postsynaptic neurone after low-frequency and high-frequency stimulation of a single presynaptic neurone, XXX.
Name and explain the type of summation shown in Figure 1.
Myasthenia gravis (MG) is an autoimmune disease where antibodies target and destroy nicotinic acetylcholine receptors on the postsynaptic membrane of neuromuscular junctions.
Suggest and explain how MG causes muscle weakness. Do not include details of muscle contraction or myofibril movement in your answer.
Pyridostigmine is a drug used to treat MG. It acts as a reversible inhibitor of acetylcholinesterase, the enzyme located in the synaptic cleft that hydrolyses acetylcholine.
Explain how Pyridostigmine can help in the treatment of MG.
