06. Tissue repair and fibrosis – Practice Quiz

Tissue Repair and Fibrosis: Regeneration, Granulation, and Scar Remodeling

When tissues suffer physical or pathological injury, the body orchestrates an intricate sequence of cellular and molecular events to restore structural integrity. This questionset explores the biology of wound healing, distinguishing true parenchymal regeneration from fibroproliferative scar repair.

Key Learning Areas

• Chronological repair phases: hemostasis, inflammatory cell influx (neutrophils transitioning to M2 macrophages), proliferation, and maturation.
• Granulation tissue: microscopic hallmarks, endothelial capillary sprouts, edematous ground substance, and contractile myofibroblasts.
• Angiogenesis: VEGF-driven endothelial tip-stalk guidance, pericyte recruitment via PDGF, and basement membrane remodeling by matrix metalloproteinases.
• Extracellular matrix remodeling: degradation of temporary Type III collagen, deposition of robust Type I collagen, and covalent cross-linking by lysyl oxidase.
• Cellular regenerative capacity: labile (epidermis, gut), stable (hepatocytes, renal tubular cells), and permanent tissues (neurons, cardiac myocytes).
• Mechanics of healing: primary vs. secondary intention, myofibroblast wound contraction, tensile strength recovery curve, and pathological keloids.
• Modulating factors: systemic influences including vitamin C, zinc, glucocorticoids, and glycemic control.

Cover image credit: Photo by Thirdman on Pexels.