Healing and Repair Flashcards
Wha is the result/effects of fibrous repair in permanent, labile and stable cells?
Permanent- always get scarring.
Labile and stable- scarring is dependent on whether the collagen framework is intact.
Define fibrous repair.
The replacement of functional tissue by scar tissue.
What does granulation tissue consist of?
Cells, blood vessels (angiogenesis) and extracellular matrix.
What cell types are found in fibrous repair?
Inflammatory cells, e.g. neutrophils and macrophages, chemical mediators, e.g. lymphocytes, endothelial cells, fibroblasts and myofibroblasts.
Talk about angiogenesis in fibrous repair. I.E. its purpose and how it occurs.
Provides access for cells delivering O2 and nutrients. The new vessels sprout from pre-existing ones. Endothelial proliferation is induced by proangiogenic growth factors. Endothelial proteolysis of basement membrane. Migration of endothelia cells by chemotaxis. Then endothelial proliferation, maturation and remodelling.
What are some of the roles of extracellular matrix in fibrous repair?
Supports and anchors cells, allows cell communication, sequesters GF and facilities cell migration.
Define regeneration.
The replacement of dead or damaged cells by functionally differentiated cells (which are derived from stem cells).
What do you understand by labile cells, and give some examples of where they are found?
State of rapid proliferation which constantly go through the cell cycle.
Found in epidermis of skin and haematopoietic cells.
What do you understand by stable cells and give some examples of where they are found?
Stable cells are normally in a resting state, i.e. G0, but when cells need replacing hey exit G0 and enter the cell cycle to proliferate.
Found in hepatocytes and osteoblasts.
What do you understand by permanent cells, and give examples of where they are found?
Permanent cells are unable to divide and remain in G0.
E.g. neurones and cardiac cells.
Discuss the healing of a clean incised skin wound (primary intention).
Apposed edges (local damage), so minimal clot and granulation tissue with little scarring. Loss of contact between epidermal cells, so loss of inhibition, hence proliferation. Dermis undergoes fibrous repair and granulation tissue matures to form scar tissue.
Discuss when and how the healing of large skin defects (secondary intention) occurs.
Occurs from infarct, ulcer, abscess or large wound. Unopposed edges, so larger clot and granulation tissue, so larger scar. Clot dries to form a scab/eschar. Epidermis regenerates from base upwards. Fibroblasts allow form wound contraction.
What is the structure of type 1 collagen?
Alpha chains crosslinked to form procollagen. Twisted structure made up of 3 chains, with a repeating pattern of glycine-X-Y.
What is the function of type 1 collagen?
To strengthen and support many tissues of the body including cartilage, bone, tendon, skin and sclera.
What are the factors that influence the efficacy of healing and repair?
Local factors- types, size, location, apposition, blood supply, infection/foreign material and radiation damage (in cancer).
General factors- age, drugs, dietary deficiencies, general health and cardiovascular status.
