axolemma

Definition

Target type: cellularcomponent

The portion of the plasma membrane surrounding an axon; it is a specialized trilaminar random mosaic of protein molecules floating within a fluid matrix of highly mobile phospholipid molecules, 7-8 nm in thickness. [http://www.medik.sk/clanky/bio_jun.htm, ISBN:0124325653]

The axolemma is the plasma membrane that encloses the axon of a neuron. It plays a crucial role in maintaining the electrochemical gradient across the axon, which is essential for nerve impulse transmission. The axolemma is composed of a phospholipid bilayer with embedded proteins. These proteins perform various functions, including ion channels, pumps, and receptors.

**Key components of the axolemma include:**

* **Phospholipid bilayer:** This forms the structural foundation of the axolemma, separating the intracellular and extracellular environments.
* **Ion channels:** These transmembrane proteins allow specific ions (sodium, potassium, calcium, etc.) to cross the axolemma, contributing to the generation and propagation of action potentials.
* **Sodium-potassium pump:** This active transport protein maintains the electrochemical gradient by pumping sodium ions out of the axon and potassium ions into the axon.
* **Voltage-gated channels:** These channels are responsible for opening and closing in response to changes in membrane potential, allowing ions to flow across the membrane and contribute to action potential propagation.
* **Ligand-gated channels:** These channels open in response to the binding of specific neurotransmitters, mediating communication between neurons at synapses.
* **Receptors:** These proteins bind to neurotransmitters, triggering intracellular signaling pathways that influence neuronal function.

**The axolemma is crucial for:**

* **Maintaining the resting membrane potential:** The axolemma establishes and maintains the electrical potential difference across the membrane.
* **Generating and propagating action potentials:** The opening and closing of ion channels in the axolemma lead to rapid changes in membrane potential, resulting in the generation and propagation of action potentials.
* **Synaptic transmission:** The axolemma contains receptors that bind to neurotransmitters released at synapses, initiating communication between neurons.

The axolemma's intricate structure and composition enable it to perform these vital functions, ensuring efficient nerve impulse transmission throughout the nervous system.'
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Proteins (8)

Compounds (238)