Count to 10 - Anaesthetic Primary Podcast EP16 – NMJ & Suxamethonium | MiniPod | CT10
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Aug 21, 2023 Explore the Neuromuscular Junction physiology and Suxamethonium pharmacology in this episode. Learn about acetylcholine, action potential pathway, ACH receptors, and Sux pharmaceutics. Dive into past SAQs focusing on Sux adverse effects and review opening viva stems. A detailed look at succinylcholine metabolism, pharmacokinetics, and potential risks associated with its administration. Understand the impact of drugs on neuromuscular junction physiology for effective management.
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Safety Margin Explains Drug Thresholds
- The NMJ has a large safety margin: only ~10% receptor activation is needed for muscle action, so non-depolarizing agents must block ~70% of receptors to impair function.
- This redundancy prevents fatigue during repeated contractions.
Adult Vs Fetal Nicotinic Receptors
- Nicotinic ACh receptors are pentameric with 2α, β, δ and ε (adult) or γ (fetal) subunits; fetal receptors stay open longer.
- Upregulated extrajunctional fetal receptors after denervation or burns cause prolonged depolarization and large K+ release risk.
Distinguish Block Types Clearly
- Differentiate block types: describe non-depolarizing, depolarizing (phase I), and phase II blocks by features like fasciculations and fade.
- Use these distinctions in vivas to explain monitoring and reversal strategies.