Generator Potential (AQA A Level Biology): Revision Note

Establishment of a generator potential in Pacinian corpuscles

• A generator potential is a change in the potential difference across the membrane of a nerve cell that occurs in response to a stimulus

  • The size of a generator potential depends on the size of the stimulus

  • If a generator potential is large enough, then it can initiate a nerve impulse, or action potential

• When Pacinian corpuscles are stimulated by pressure on the skin, a generator potential is established as follows:

  1. pressure distorts the layers of membrane, causing stretch-mediated sodium channels in the axon membrane to open

  2. sodium ions enter the axon via facilitated diffusion

  3. positively charged sodium ions cause the inside of the axon to become more positive; this is a generator potential