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Neurons - Anatomy & Physiology (view source)
Revision as of 08:12, 25 August 2011
, 08:12, 25 August 2011→Nerve Impulse Propagation
The term "oligodendrocyte" literally means a "cell with many branches". Oligodendrocyte precursors are found throughout the CNS and these precursors are post-mitotic, meaning oligodendrocytes can be replaced. Oligodendrocytes can [[PNS Structure - Anatomy & Physiology#The Process of Myelination|myelinate]] up to 40 axons at a time. The myelin sheath formed by oligodendrocytes has numerous functions including; decreasing any ion leakage from the axon lowering the capacitance of the cell membrane and increasing impulse speed along the axon by allowing saltatory conduction of action potentials between the nodes of Ranvier.
The term "oligodendrocyte" literally means a "cell with many branches". Oligodendrocyte precursors are found throughout the CNS and these precursors are post-mitotic, meaning oligodendrocytes can be replaced. Oligodendrocytes can [[PNS Structure - Anatomy & Physiology#The Process of Myelination|myelinate]] up to 40 axons at a time. The myelin sheath formed by oligodendrocytes has numerous functions including; decreasing any ion leakage from the axon lowering the capacitance of the cell membrane and increasing impulse speed along the axon by allowing saltatory conduction of action potentials between the nodes of Ranvier.
===Nerve Impulse Propagation===
===Nerve Impulse Propagation===
Nerves are able to create, amplify and propogate electrical impulses that run along their axon. These nerve impulses are a form of action potential that is carried by ions. The nerve impulse is in effect an electrical difference between the inside and outside of the axon and is caused by ion movements across the membrane.
Nerves are able to create, amplify and propogate electrical impulses that run along their axon. These nerve impulses are a form of action potential that is carried by ions. The nerve impulse is in effect an electrical difference between the inside and outside of the axon and is caused by ion movements across the membrane. Nerve impulses can occur from a number of sources including sensiry cells, action potentials from other connected nerves or spontaneous depolarisation of the nerve cell membrane.
====Unmyelinated Axons====
Conduction of an action potential along an unmyelinated axon, i.e. an axon not covered by some form of glial cell, is a much slower form of nerve impulse propagation than that of a myelinated axon.
Nerve impulses can occur from a number of sources including sensiry cells, action potentials from other connected nerves or spontaneous depolarisation of the nerve cell membrane.
====Myelinated Axons====
==Astrocytes==
==Astrocytes==