A pseudounipolar neuron (pseudo - false, uni - one) is a sensory neuron in the peripheral nervous system. This neuron contains a long dendrite and a short axon that connects to the spinal cord. The dendrite and axon are sometimes called distal process and proximal process, respectively.^[1]

Contents 1 The dendrite of a pseudounipolar neuron 2 Anatomy 3 Signal Pathway 4 References 5 External links

[edit] The dendrite of a pseudounipolar neuron

By definition a pseudounipolar neuron has one axon with 2 processes: a central and a peripheral process. Not to be confused with a dendrite. Like every neuron, the dendrite conducts nerve impulses toward the cell body, and the axon conducts them away from the cell body. However, the dendrite of a pseudounipolar neuron is structurally and functionally an axon, except at its terminal part where it contacts a specialized sensory organ.^[2] When the sensory organ transduces information, it initiates an action potential that is propagated toward the cell body. Because the dendrite functions as an axon, this potential does not degrade, but reaches the axon unabated and then continues toward the central nervous system.^[1]
Because of the similarity between this dendrite and an axon, some authors describe the pseudounipolar neuron as having one process that leaves the cell body, an axon. The dendrites are placed "on top of" the axon, connected with the receptors.^[3]
In pictures, the dendrite can be both called dendrite^[4] and axon.^[2] Both the axon and the dendrite/axon are myelinated.

[edit] Anatomy

The cell bodies are located in the dorsal root ganglion. The axon goes out of the cell body (and out of the D.R.G) into the dorsal root, where it splits into two branches: One branch goes to the posterior horn of the spinal cord ("the axon"), and the other goes along the distal dorsal root, into the spinal nerve all the way until its sensational ending ("the dendrite").

[edit] Signal Pathway

The signal is conducted through the dendrite to the dorsal root ganglion's cell body, then through the axon and ending at the sensory nuclei in the dorsal horn of the spinal cord.

[edit] References

[edit] External links

• Diagram at ccccd.edu

• unipolar+neuron at eMedicine Dictionary

v • d • e Histology: nervous tissue (TA A14.2.00, GA 9.849) Neurons (grey matter) Parts soma axon (axon hillock, axon terminals, axoplasm, axolemma, neurofibril/neurofilament) dendrite (Nissl body, dendritic spine, apical dendrite, basal dendrite) Types bipolar · pseudounipolar · multipolar · pyramidal · Purkinje · granule Afferent nerve fiber/ Sensory nerve GSA · GVA · SSA · SVA fibers (Ia, Ib or Golgi, II or Aβ, III or Aδ or fast pain, IV or C or slow pain) Efferent nerve fiber/ Motor nerve GSE · GVE · SVE Upper motor neuron · Lower motor neuron (α motorneuron, γ motorneuron) Termination Synapses neuropil · synaptic vesicle Interneuron (Renshaw) · neuromuscular junction · electrical synapse Sensory receptors Meissner's corpuscle · Merkel nerve ending · Pacinian corpuscle · Ruffini ending · Muscle spindle · Free nerve ending · Olfactory receptor neuron · Photoreceptor cell · Hair cell · Taste bud Support Glial cells Astrocyte (Radial glia) · Oligodendrocyte · Ependymal cells (Tanycytes) · Microglia Myelination (white matter) CNS: Oligodendrocyte PNS: Schwann cell · Neurolemma · Nodes of Ranvier/Internode · Schmidt-Lanterman incisures Related connective tissues epineurium · perineurium · endoneurium · nerve fascicle · meninges Other Posterior (Root, Ganglion, Ramus) · Anterior (Root, Ramus) · rami communicantes (Gray, White) · Preganglionic fibers · Postganglionic fibers · Lemniscus · Funiculus · Fasciculus · Decussation · Commissure Projection fibers · Association fiber · Commissural fiber peripheral nervous system navs: anat/histo/physio/dev, noncongen PNS somatic/autonomic/congen/neoplasia, symptoms+signs/eponymous, proc

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