FoundationalConceptsNeuroscience

DRG cell body

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Dendrite with Axon to spinal cord

somatosensory receptors and brainstem

Figure 16.2. Dorsal root ganglion cells, with dendrite nerve fibers innervating
the skin and axons that send signals into the central nervous system.

Receptors responsive to touch and poking are presumed to be based
on some sort of mechanically-gated ion channels, perhaps similar to
the channels on inner ear hair cells that open as the hairs bend. The
receptors responsive to temperature changes are the very same TRP
receptors described in Chapter 13 that are related to the flavor percep-
tions of spicy hot and minty cool.
The cell bodies for these fibers are located in clusters of cells near
the spinal cord called the dorsal root ganglia (DRG). The DRG nerve
fibers innervating the skin are contiguous with the axons that send
signals into the central nervous system (Fig. 16.2). The peripheral
dendrites also contain voltage-gated sodium and potassium channels
and are myelinated. Thus, when sensory receptor proteins are acti-
vated by the relevant physical stimuli, they generate action potentials
that propagate toward the DRG, bypass the cell body, and continue