Pseudounipolar neuron

Pseudounipolar neuron

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.http://neuro.vetmed.ufl.edu/neuro/neurocl.htm]

The dendrite of a pseudounipolar neuron

By definition a pseudounipolar neuron has one dendrite and one axon. 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. [http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=mcb.figgrp.6110 Structure of typical mammalian neurons ] ] 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 continues toward the central nervous system.
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. [http://webanatomy.net/anatomy/neuron_types.jpg
]
In pictures, the dendrite can be both called dendrite [http://universe-review.ca/I10-40-nerve.jpg] and axon. Both pictures show that this dendrite/axon is myelinated.

Anatomy

The dendrite of these neurons is located in the nerves coming from the body. The cell bodies are located in the dorsal root ganglion just next to the spinal cord. The axons protrude through the dorsal root and into the posterior horn of the spinal cord.

ignal Pathway

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

References

External links

* [http://iws.ccccd.edu/mweis/Images/Fireworks%20Drawings/2401%20related%20drawings/drawings%20in%20fireworks/nervous,%20ss,%20integ/nervous/drw_nervous_pseudounineuron_labeled.pngDiagram at ccccd.edu]
*
*


Wikimedia Foundation. 2010.

Игры ⚽ Нужна курсовая?

Look at other dictionaries:

  • pseudounipolar neuron — a unipolar neuron, almost always a primary sensory neuron, that was originally bipolar but whose two processes fused during development to form a single process that bifurcates at a distance from the cell body. One branch is structurally an axon… …   Medical dictionary

  • pseudounipolar neuron — noun A neuron in the peripheral nervous system having a long dendrite and a small axon that connects to the spinal cord …   Wiktionary

  • Neuron — A nerve cell, the basic impulse conducting unit of the nervous system. Neurons send and receive electrical signals over long distances within the body. A neuron may send electrical output signals to muscle neurons (called motor neurons or… …   Medical dictionary

  • Neuron — This article is about cells in the nervous system. For other uses, see Neuron (disambiguation). Brain cell redirects here. For other uses, see Glial cell. Neuron: Nerve Cell …   Wikipedia

  • pseudounipolar — adjective Of a neuron, having one axon that is split into two branches …   Wiktionary

  • Sensory neuron — Sensory neurons are neurons that are activated by sensory input (vision, touch, hearing, etc.), and send projections into the central nervous system that convey sensory information to the brain or spinal cord. Unlike neurons of the central… …   Wikipedia

  • Unipolar neuron — A unipolar neuron is a type of neuron in which only one protoplasmic process (neurite) extends from the cell body. Most neurons are multipolar, generating several dendrites and an axon: unipolar neurons are exceptions to this rule.Unipolar… …   Wikipedia

  • primary sensory neuron — a sensory neuron that is the first in an afferent pathway, beginning at the receptor and ending at a synapse with a secondary sensory neuron, often within a nucleus of the central nervous system. One common type is the pseudounipolar neuron …   Medical dictionary

  • Motor neuron — Neuron: Motor neuron Micrograph of the hypoglossal nucleus showing motor neurons with their c …   Wikipedia

  • Olfactory receptor neuron — Neuron: Olfactory receptor neuron Labels in German. Zellen = cell , riech = smell , Riechnerv = olfactory nerve, cillien = cilia …   Wikipedia

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”