Pathophysiology
Clinical meaning
Wound healing is a complex, overlapping biological process that occurs in four distinct but interrelated phases: hemostasis, inflammation, proliferation, and maturation (remodeling). Hemostasis begins immediately upon tissue injury and lasts approximately 5 to 10 minutes. When a blood vessel is damaged, vasoconstriction occurs as the first response to reduce blood loss. Platelets adhere to exposed collagen in the vessel wall, aggregate together, and form a platelet plug. The coagulation cascade is activated, converting fibrinogen to fibrin, which stabilizes the platelet plug into a clot. This clot serves as a temporary matrix for cell migration in subsequent phases. The inflammatory phase begins within hours of injury and typically lasts 1 to 6 days. Neutrophils are the first white blood cells to arrive at the wound site (within 6 to 8 hours), where they phagocytize bacteria and debris. Macrophages follow within 24 to 48 hours and are considered the most critical cells in wound healing because they not only continue phagocytosis but also release growth factors (such as platelet-derived growth factor, transforming growth factor-beta, and vascular endothelial growth factor) that recruit fibroblasts...