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A-Level Biology OCR A

Sodium Potential Neurone Corpuscle Membrane Ions Pacinian Pressure

Pressure on a Pacinian corpuscle widens the sodium ion channels in the sensory neurone membrane, causing an influx of sodium ions. This depolarization generates a generator potential, which can lead to an action potential.

Pressure on a Pacinian corpuscle widens the sodium ion channels in the sensory neurone membrane, causing an influx of sodium ions. This depolarization generates a generator potential, which can lead to an action potential.

Front Explain how a Pacinian corpuscle converts mechanical pressure into a nerve impulse.
Back Pacinian corpuscle mechanism:
  • In normal (resting) state - stretch mediated sodium ion channels in sensory neurone membrane are too narrow to allow sodium ions to pass through them - it has resting potential
  • When pressure applied, corpuscle changes shape causing membrane surrounding the neurone to stretch
  • This causes sodium ion channels to widen, allowing sodium ions to diffuse into neurone
  • Influx of positive sodium ions changes potential of the membrane - it becomes depolarised resulting in generator potential
  • Generator potential creates action potential that passes along sensory neurone

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