394
UNIT 3
Regulation and Integration of the Body
11
Table 11.1
Comparison of Structural Classes of Neurons
NEURON TYPE
MULTIPOLAR
BIPOLAR
UNIPOLAR (PSEUDOUNIPOLAR)
Structural Class: Neuron Type According to the Number of Processes Extending from the Cell Body
Many processes extend from the cell body. All are
dendrites except for a single axon.
Two processes extend from the cell body.
One is a fused dendrite, the other is an
axon.
One process extends from the cell
body and forms central and peripheral
processes, which together comprise an
axon.
Relationship of Anatomy to the Three Functional Regions
 
(Many bipolar neurons do not generate
action potentials. In those that do,
the location of the trigger zone is not
universal.)
 
Relative Abundance and Location in Human Body
Most abundant in body. Major neuron type in the CNS.
Rare. Found in some special sensory
organs (olfactory mucosa, eye, ear).
Found mainly in the PNS. Common only
in dorsal root ganglia of the spinal cord
and sensory ganglia of cranial nerves.
Structural Variations
Cell body
Dendrites
Axon
Cell body
Dendrite
Axon
Receptive
endings
Cell body
Peripheral
process
Central
process
Axon
Trigger zone
Receptive region (receives stimulus).
Conducting region (generates/transmits action potential).
Secretory region (axon terminals release neurotransmitters).
Trigger zone
Trigger zone
Cell body
Purkinje cell of
cerebellum
Axon
Cell
body
Axon
Dendrites
Multipolar
Pyramidal cell
Cell
body
Axon
Olfactory cell
Dendrite
Cell
body
Axon
Retinal cell
Bipolar
Unipolar
Receptive
endings
Peripheral
process
(axon)
Cell
body
Central
process
(axon)
Dorsal root ganglion cell
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