Describe the physiology of skeletal muscle cell contraction.
This question required a description of excitation- contraction coupling. Marks were gained
for a brief outline of the structure of a sarcomere and how it facilitates shortening. An
explanation of membrane processes, receptor interactions and the contraction processes was
required. Mention of the role of ATP was also required and marks were gained for
commenting on the mechanism of return to the relaxed state.
Most candidates wrote extensively on the nerve action potential and neuromuscular junction
transmission, with minimal reference to events occurring within the skeletal muscle cell
membrane. They could not gain marks for this. Few candidates demonstrated knowledge of
the ATP dependent walk along processes of myosin heads during contraction.