Tissue Repair, Regeneration, Healing, and Fibrosis

Flashcards covering tissue repair, regeneration, wound healing, bone healing, and nervous system repair based on the lecture notes.

Repairing

The restoration of tissue architecture and function after an injury.

Regeneration

The replacement of damaged components to essentially return the tissue to a normal state.

Healing

The laying down of connective (fibrous) tissue at a site of injury when injured tissues are incapable of complete restitution or supporting structures are severely damaged, resulting in scar formation.

Fibrosis

The extensive deposition of collagen that occurs in organs such as the lungs, liver, and kidneys as a consequence of chronic inflammation.

Labile cells

Cells that have sustained proliferation under normal conditions, including epidermis, lining epithelium of GI, respiratory, and urogenital tracts, and red and white blood cells.

Stable cells

Cells that are unable to proliferate under normal conditions due to a fixed cell count, but proliferate when tissue is damaged or resected, such as liver, renal tubules, and mesenchymal tissue.

Permanent cells

Special and highly differentiated cells that have lost the ability to divide, such as cardiac muscle cells and nerve cells.

Healing by first intention

Wound healing that occurs in clean surgical wounds in sterile areas with minimal damage, where edges are closely approximated by suture and bleeding is minimal.

Healing by second intention

Wound healing that occurs when there is extensive tissue destruction with an inability to achieve apposition of wound margins, resulting in a large amount of granulation tissue and a large scar.

Myofibroblasts

Cells responsible for achieving wound contraction.

Granulation tissue

Vascular tissue formed during wound healing starting around the third day through angiogenesis and fibroblast proliferation.

Keloid

A prominent raised scar due to excessive collagen formation, more frequently seen in black individuals, with an unknown cause that may involve a heritable factor.

Sinus

An infected tract leading from a focus of infection to the surface of the skin or a hollow organ.

Fistula

An abnormal communication between two hollow organs or between a hollow organ and the exterior.

Wound contracture

A complication caused by the thickening and shortening of collagen bundles that causes serious cosmetic and functional disability, such as following extensive burns or near a joint.

Soft callus

Soft granulation tissue formed during bone healing when a hematoma is invaded by capillary loops and mesenchymal cells derived from the periosteum and endosteum.

Provisional callus

A hardened structure formed within about $3\text{--}4\text{ weeks}$ of a fracture as mesenchymal cells begin forming bone and cartilage in the soft callus.

Gliosis

The repair process in the central nervous system where dead cells are removed by microglia and replaced by neuroglia cells.

Axonal degeneration

A type of degeneration occurring after peripheral nerve injury that affects the nerve cell body.

Wallerian degeneration

A type of degeneration in peripheral nerve injury that affects all of the distal fragment and the proximal fragment up to the level of the first node of Ranvier.