The Pacinian corpuscle is a type of receptor found in the dermis of the skin. Pacinian corpuscles contain an ending of a sensory neurone, surrounded by several layers of connective tissue called a capsule. The activity of a Pacinian corpuscle was investigated by inserting microelectrodes into the axon at the positions shown in the diagram below.

Pressure was applied to the Pacinian corpuscle and recordings made of the electrical activity in the axon at microelectrodes A and B. The results are shown in the diagram below.

a. Suggest what happened in the unmyelinated region of the axon as pressure was applied to the Pacinian corpuscle.

b. Explain the pattern of recordings from microelectrode B as the pressure applied to the corpuscle was increased.

c. Explain why sensory neurones from Pacinian corpuscles are myelinated and not unmyelinated.

Transcribed Image Text:

microelectrode A microelectrode B pressure (stimulus) capsule containing many collagen fibres unmyelinated endings of sensory аxon neurone