Neuro Atlas

Cutaneous Receptors: Pacinian Corpuscle
NEUROPHYSIOLOGY
Pacinian Corpuscle
as Pressure Transducer
To amplifier
Pressure
Generator potential
Action potential
A. Sharp “on and off” changes in pressure at start and end
1st node
Pressure Na + of pulse applied to lamellated capsule are transmitted to
Myelin sheath central axon and provoke generator potentials, which in
Lamellated capsule
turn may trigger action potentials; there is no response to a
slow change in pressure gradient. Pressure at central core
Central core
Unmyelinated axon terminal
and, accordingly, generator potentials are rapidly dissipated
by viscoelastic properties of capsule (Action potentials may
be blocked by pressure at a node or by drugs)
Pressure
To amplifier
Generator potential
B. In absence of capsule, axon responds to slow as well
as to rapid changes in pressure. Generator potential
dissipates slowly, and there is no “off” response
Action potential
Pressure applied to axon terminal directly or
via capsule causes increased permeability of
membrane to Na + , thus setting up ionic
generator current through 1st node
If resultant depolarization at 1st node is great
enough to reach threshold, an action potential
appears which is propagated along nerve fiber
©
FIGURE 2.24
PACINIAN CORPUSCLE •
Pacinian corpuscles are mechanoreceptors that transduce mechanical
forces (displacement, pressure, vibration) into action potentials
that are conveyed centrally by afferent nerve fibers. As the viscoelastic
lamellae are displaced, the unmyelinated axon terminal
membrane’s ionic permeability is increased until it is capable of
producing a “generator potential.” As demonstrated in the figure,
pacinian corpuscles respond to the beginning and end of a
mechanical force while the concentric lamellae dissipate slow
changes in pressure. In the absence of the capsule, the generator
potential decays slowly and yields only a single action potential.
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