The Pacinian corpuscle - a simple receptor

---

This section is best read after The sensory cell.

It is intended to illustrate what has been presented so far.

---

Pacinian corpuscles are present in the skin, some mucous membranes etc. They are mechanoceptors, responding to pressure, or any kind of mechanical stimulus causing a deformation of the corpuscle.

The Pacinian corpuscle has a single afferent nerve fiber. Its end is covered by a sensitive receptor membrane whose sodium channels will open when the membrane is deformed in any way. It is surrounded by several concentric capsules of connective tissue, with a viscous gel between them.

In the resting state, a cross-section through the corpuscle looks something like this:

Now, if the skin over the corpuscle is touched, it will be deformed and make a nuisance of itself:
 
But the viscous gel between the capsules will move and allow the nerve ending to resume its normal shape:
If the pressure is now released, the corpuscle as a whole will resume its original shape, but the nerve ending will be deformed in the process:
 
But the viscous gel will then flow back, and soon we are back at the beginning.

Summarizing this as a potential vs. time diagram:

We can see that the Pacinian corpuscle has a dynamic behaviour.

---

The Pacinian corpuscle responds particularly to vibration. You understand why?

---