University:
Camosun College
Course:
BIOL 252 | Pathophysiology for Nursing 1
Academic year:

2024
Views:

309

Pages:

2
Author:

Aysha A.

Pathophysiology of Demyelination: Demyelination: Loss or damage of myelin sheath covering the axon. Normal Myelination: Myelin sheaths mask voltage-gated ion channels, particularly Na+ channels. Conduction of action potential (AP) is rapid (up to 120 m/s) and occurs through saltatory conduction, jumping from one Node of Ranvier to the next. Impact of Demyelination: Voltage-gated ion channels (Na+, K+, Ca2+) are normally masked by the myelin sheath. Demyelination exposes these channels, leading to the leakage of ions, particularly K+. This leakage causes a drop in the intracellular potential, preventing the further conduction of the AP. The AP fails to reach the axon terminal, where normally it would lead to Ca2+ influx, triggering neurotransmitter release (exocytosis). Consequence: Slowed or blocked conduction of the AP, resulting in slower neuronal transmission and reduced neurotransmitter release. The conduction speed drops to as low as 1 m/s. Neurological symptoms arise due to impaired neuronal communication. This explains the physiological basis for conditions like Multiple Sclerosis, where demyelination leads to progressive neurological deficits.