Dermatology

The core mechanism involves the rupture of an unstable atherosclerotic plaque in the coronary artery. This triggers the coagulation cascade and the formation of a thrombus that causes sudden occlusion.

Myocardial cells distal to the obstruction experience anaerobic metabolism, leading to lactic acid accumulation and intracellular edema. Within 20-40 minutes, irreversible cell death begins at the subendocardium...

The classic "wavefront" phenomenon of necrosis then spreads toward the epicardium. Systemic inflammatory responses initiate cellular remodeling that eventually leads to fibrosis...

The SA node exhibits automaticity due to the 'funny current' (If) mediated by HCN channels. These channels open during hyperpolarization, allowing a slow influx of sodium ions...

Unlike ventricular myocytes, the depolarization phase (Phase 0) is primarily driven by the influx of Calcium ions through L-type calcium channels, rather than fast sodium channels...

Repolarization (Phase 3) occurs as calcium channels close and delayed rectifier potassium channels open, allowing K+ to exit the cell. This cycle repeats spontaneously...