List two stimuli and the receptors that detect them.

Outline how pain is perceived and the role of endorphins in this process.

a. pressure/movement/sound (detected by) mechanoreceptors;

b. chemicals (detected by) chemoreceptors;

c. temperature (detected by) thermoreceptors;

d. light (detected by) photoreceptors;

e. pain (detected by) nocireceptors;

f. stretch/orientation/movement (detected by) proprioreceptors;

a. impulses passed from pain receptors to sensory areas;

b. of the cerebral cortex where pain is perceived / feelings of pain in the areas of the cerebral cortex;

c. endorphins act as painkillers;

d. which block transmission of impulses at the synapses involved in pain transmission;

A large majority could list stimuli and receptors, but a significant number gave very general answers, for example sound in ears.

Weaker candidates were more likely to describe the pain withdrawal reflex rather than how pain is perceived. In (c) most candidates earned at least one mark outlining how pain is perceived. The most common response was that endorphins act as painkillers.