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Concept
Axolemma
Résumé
In neuroscience, the axolemma (, and 'axo-' from axon) is the cell membrane of an axon, the branch of a neuron through which signals (action potentials) are transmitted. The axolemma is a three-layered, bilipid membrane. Under standard electron microscope preparations, the structure is approximately 8 nanometers thick.
The skeletal framework of this structure is formed by a spectrum of hexagonal or pentagonal arrangement on the inside of the cell membrane, as well as actin connected to the transmembrane. The metric cellular matrix is bound by transmembrane proteins, including the β1-integrin, to the cytoskeleton via the membrane skeleton. The axolemma is a phospholipid bilayer membrane, and charged ions/particles cannot directly pass through it. Instead, transmembrane proteins, such as specialized energy dependent ion pumps (the sodium/potassium pump), and ion channels (ligand-gated channels, mechanically gated channels, voltage-gated channels, and leakage channels) that sit within the axolemma are required to assist these charged ions/particles across the membrane, and to generate transmembrane potentials that will generate an action potential.
The primary responsibility of cell membranes, including those surrounding the axon, is to regulate what goes into the cell and what goes out of the cell. The axolemma plays an important role in the nervous system, specifically the sensation, integration, and response pathways within the nervous system. Communication between neurons within the nervous system relies on excitable membranes, especially the axolemma. The axolemma is responsible for relaying signals between the neuron and it's Schwann Cells. These signals control the proliferative and myelin-producing functions of the Schwann Cells, and also partly play a role in the regulation of the size of the axon.
The variations in electrical state of the axolemma is referred to as the membrane potential – a potential being the distribution of charge between the inside and outside of the cell, which is measured in millivolts (mV).
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