The Pacinian corpuscle should be used as an example of a receptor to illustrate that:

- receptors respond only to specific stimuli
- stimulation of a receptor leads to the establishment of a generator potential.

The basic structure of a Pacinian corpuscle.

Deformation of stretch-mediated sodium ion channels in a Pacinian corpuscle leads to the establishment of a generator potential.

The human retina in sufficient detail to show how differences in sensitivity to light, sensitivity to colour and visual acuity are explained by differences in the optical pigments of rods and cones and the connections rods and cones make in the optic nerve.