â– PHYSIOLOGICAL CORE: Myelination is a cellular adaptation that significantly increases the speed of action potential propagation along axons without requiring increases in axonal diameter.
â– BIOPHYSICAL PROPERTIES:
1. Myeline Layers: Composed of concentric layers of glial cell membranes: Schwann cells in the peripheral nervous system (PNS) and Oligodendrocytes in the central nervous system (CNS).
2. Resistance & Capacitance: Myelin acts as an electrical insulator, increasing membrane resistance and decreasing membrane capacitance.
3. Nodes of Ranvier: The myelin sheath is interrupted every 1-2 mm by unmyelinated gaps called Nodes of Ranvier, which express high densities of voltage-gated sodium and potassium channels.
4. Saltatory Propagation: Instead of a continuous wave, the depolarizing charge jumps from node to node (saltatory conduction), accelerating conduction velocity.
â– BIOCHEMICAL MECHANISMS:
At the molecular level, enzyme kinetics govern reaction rates. Competitive inhibitors raise apparent Michaelis constants without changing maximum speed, whereas noncompetitive inhibitors decrease maximum speed directly.
â– SECONDARY PREVENTION METRICS:
Implementing long-term dietary adaptations, physical therapy, and compliance aids reduces the rate of recurring acute crises by more than half.
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🌟 Dynamic Clinical Key:
In Multiple Sclerosis, autoimmune destruction of oligodendrocytes causes demyelination in the CNS. This degrades saltatory conduction, causing action potential delay or failure, presenting with diverse neurologic deficits like sensory loss, weakness, or optic neuritis. Focus on rate-limiting regulatory steps for pharmacological design. Patient education regarding warning signs and therapy adherence is the cornerstone of secondary prevention.