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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 via synapses with axons from other nerve cells. In most cases nerve impulses travel from other nerve cells to the cell body and are then conducted along the nerve cell's own axon to other cell bodies. However, dendrites themselves are unable to propagate nerve impulses in the manner of axons as dendrites are unable to secrete [[Neurotransmitters_-_Anatomy_%26_Physiology|neurotransmitters]]. Similarly axons do not possess the chemoreceptors that are found within the dendrites and are therefore unable to receive nerve impulses. Nerve impulses are therefore conducted in one direction only.

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 via synapses with axons from other nerve cells. In most cases nerve impulses travel from other nerve cells to the cell body and are then conducted along the nerve cell's own axon to other cell bodies. However, dendrites themselves are unable to propagate nerve impulses in the manner of axons as dendrites are unable to secrete [[Neurotransmitters_-_Anatomy_%26_Physiology|neurotransmitters]]. Similarly axons do not possess the chemoreceptors that are found within the dendrites and are therefore unable to receive nerve impulses. Nerve impulses are therefore conducted in one direction only.

[[Image:neurondiagram.jpg|thumb|right|150px|Diagram of a neuron. LadyofHats, '''Wikimedia Commons''', 2007]]

[[Image:neurondiagram.jpg|thumb|right|150px|Diagram of a neuron. LadyofHats, '''Wikimedia Commons''', 2007]]

====Axon====

===Axon (Nerve Fibre)===

 

The axon is a very fine projection that can measure up to thousands of time the soma diameter in length. The axon carries nerve signals away from the soma. The structure and function of the axon is very similar between the CNS and the PNS. This has been covered in detail within the PNS Structure and Anatomy page so for further information please click [[PNS_Structure_-_Anatomy_%26_Physiology#Structure|here]].

* The axon is a very fine projection that can measure up to thousands of time the soma diameter in length.

* The axon carries nerve signals away from the soma.

* The axon emerged from the soma at the axon hillock

** The axon and axon hillock are generally involved in information outflow.

* At the end of the axon, there are synapses.

* The axon is dependent on the cell body for all its metabolic functions.

** The axon has no Nissl substance: it cannot make its own protein, and so the soma must undertake this function.

** Death or damage to the cell body will therefore result in axon compromise or degeneration

 

 

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

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

** There is therfore variation in the size, shape, structure, metabolism, function shape and electrochemical properties between locations.

==Astrocytes==

==Astrocytes==