Burn injuries create three concentric zones of tissue damage (Jackson's burn wound model). The zone of coagulation (center) has irreversible protein denaturation and cell death. The zone of stasis (surrounding) has reduced perfusion with potentially viable tissue that can be salvaged with adequate resuscitation. The zone of hyperemia (outermost) has increased blood flow and recovers fully. The systemic response to major burns includes massive capillary leak (third-spacing), releasing inflammatory mediators (histamine, bradykinin, prostaglandins) that increase vascular permeability. This causes intravascular volume depletion, edema, and hypovolemic shock. The Parkland formula guides crystalloid resuscitation: 4 mL x kg x %TBSA burned in the first 24 hours, with half given in the first 8 hours from the time of burn (not from arrival).