feel something sharp, the sensory neurons of the PNS send
information to the CNS. An impulse begins at the dendrites of
these neurons. The impulse travels through the cell body, then
through the myelinated axon, where it quickly jumps from
node to node. The dendrites of another neuron receive the
messages and this pattern continues. The information is
directed to the CNS, where interneurons assist in analyzing
and interpreting the information. The CNS says, “We are
touching something that could be harmful. We cannot touch it
anymore.” The CNS then sends messages back to the PNS
using motor neurons. The impulse travels down the dendrites,
cell body, and axon of each neuron until it reaches its target.
In this case, the autonomic nervous system sends a message to
the muscles in your hand because this system is determined to
protect you. Involuntarily, you pull your hand away. The
nervous system has accomplished its immediate mission, but it
continues working because it has other very busy and
important jobs.