Describe the mechanism of action of the analgesic effect of opiates. (70% of marks) Explain the mechanism by which morphine causes respiratory depression and constipation. (30% of marks)
This question was poorly answered with a low pass rate; which was unexpected for this core
topic. In general, completed answers demonstrated good understanding of the analgesic
mechanisms of opiates, but only superficial understanding of respiratory depression and
constipation. Better answers explained the decreased responsiveness of the respiratory
centre to CO2, and the effects of opiates on the enteric nervous system and peristalsis.