Wound Healing Stages and Tissue Repair - Anatomy and Physiology
- What is the difference between regeneration and fibrosis in tissue repair?
- Regeneration replaces damaged tissue with the same cell type; fibrosis replaces it with collagen-rich scar tissue.
- What forms the provisional matrix during the hemostasis phase of wound healing?
- The fibrin clot, which stops bleeding and serves as a scaffold for incoming cells.
- What are labile cells?
- Cells that divide continuously throughout life, such as epidermal and gastrointestinal epithelium, so these tissues regenerate readily.
- Hepatocytes are normally quiescent but can divide after injury. How are they classified by regenerative ability?
- Stable cells. They rest in G0 but re-enter the cell cycle when tissue is lost.
- What is granulation tissue made of?
- New capillaries, proliferating fibroblasts and inflammatory cells in a loose matrix.
- How long can the remodeling phase of wound healing last?
- Months to a year or more.
- Which cells lay down collagen during the proliferative phase?
- Fibroblasts, which produce collagen and other extracellular matrix.
- What happens to collagen during the remodeling phase?
- Type III collagen is replaced by stronger type I collagen, and fibers are reorganized and cross-linked.
- After a myocardial infarction, what replaces the dead cardiac muscle?
- Fibrous scar tissue, because cardiac muscle cells are permanent cells with very limited ability to divide.
- Which cell type is central to the shift from inflammation to proliferation?
- The macrophage, which clears debris and secretes growth factors that attract fibroblasts and stimulate angiogenesis.
- In the four-phase model, what are the phases of wound healing in order?
- Hemostasis, inflammation, proliferation, and remodeling (maturation).