Changes

==Neurons==

==Neurons==

A typical neuron can be exmplified by a motor neuron in which the cell body of the nerve is located within the gray matter of the spinal cord and the nerve fibre, or axon, extends to the muscle.

A typical neuron can be exmplified by a motor neuron in which the cell body of the nerve is located within the gray matter of the spinal cord and the nerve fibre, or axon, extends to the muscle. Nerve '''axons''' can be very long permitting electrical impulses to be sent over long distances throughout the body. The information below specifically regarding neurons is inter-changable between the CNS and PNS and therefore links have been provided where appropriate on this page to the [[PNS_Structure_-_Anatomy_%26_Physiology|'''PNS Structure''']] page where information specific to the PNS can be found.  

* Neurons are the functional cells of both the CNS and PNS.

** They are highly specialised to process and transmit signals.  

Structure:

===Basic Nerve Structure===

====Soma====

===Soma===

 

The soma, or cell body is the central part of the neuron and contains the nucleus of the cell, the rough and smooth endoplasmic reticulum, ribosomes and golgi apparatus. Similar processes that would be undertaken by any cell occur within the soma and due to the organelles it contains, the soma is where most protein synthesis occurs.

* The soma, or cell body is the central part of the neuron.

===Dendrites===

* The soma contains:

The neuron's dendrites are effectively branching extensions of the cell body. Collectively, these branching structures of the dendrites is known as the "dendritic tree". The dendritic tree is the site where input to the neuron occurs. Information outflow can also occur in the reverse direction, from the soma to the dendrites. However, information is not transmitted from the dendrites in this way, because axons do not possess chemoreceptors and dendrites cannot secrete neurotransmitter chemicals.

** The nucleus

** Smooth and rough endoplasmic reticulum

** Golgi apparatus

** Due to the organelles it contains, the soma is where most protein synthesis occurs.

 

====Dendrites====

 

* The neuron's dendrites are branching extensions of the cell body.

** Collectively, branching structure of the dendrites is known as the "dendritic tree".

* The dendritic tree is the site where input to the neuron occurs. [[Image:neurondiagram.jpg|thumb|right|150px|Diagram of a neuron. LadyofHats, '''Wikimedia Commons''', 2007]]

* Information outflow can also occur in the reverse direction, from the soma to the dendrites.

** However, information is not transmitted from the dendrites in this way, because axons do not possess chemoreceptors and dendrites cannot secrete neurotransmitter chemicals.

*** Nerve impulses are therefore conducted in one direction only.

*** Nerve impulses are therefore conducted in one direction only.

 

====Axon====

====Axon====