The generator potential in a Pacinian corpuscle, a rapidly-adapting mechanoreceptor, adapts quickly because:

• A The lamellated capsule mechanically filters static deformation; only dynamic changes (onset/offset) deform the nerve ending sufficiently to generate a receptor potential ✓
• B Voltage-gated Na+ channels at the Pacinian corpuscle node of Ranvier inactivate rapidly
• C High-threshold Ca2+ channels at the sensory ending inactivate within milliseconds
• D K+ conductance rapidly repolarises the receptor membrane after each stimulus

Explanation

Pacinian corpuscles are rapidly adapting because their onion-like lamellar capsule acts as a high-pass mechanical filter. When a sustained pressure is applied, the lamellae redistribute the deforming force away from the central nerve ending, so the ending returns to its resting geometry despite continued pressure — no receptor potential is generated. Only the dynamic phases (onset and offset of the stimulus) produce sufficient mechanical deformation to open mechanosensitive channels (Piezo2) and generate a generator potential. This capsular filtering, not ion channel kinetics, is responsible for rapid adaptation in Pacinian corpuscles.

Reference: Guyton & Hall, Textbook of Medical Physiology, 14th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.