Term
| Chronic Inflammation: General |
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Definition
-3 stages:
1.tissue infiltration with lymphocytes, plasma cells and Mo (may have some No)
2.tissue destruction
3.repair by proliferation of connective tissue and new BV's
-3 catergories for chronic inflammation inciting factors
1.Persistent infections
2.Prolonged exposure
3.Autoimmune disease
-Chronic inflammation types are divided into 2 categories depending on the cells present:
1.Granulomatous inflmmation: monocyte-macrophage dominant and take the form of:
a.Macrophages
b.Epitheloid macrophages- originate from Mo and are identified by the large amount of cytoplasm which causes them to look like epithelial squamous cells.
c.multinucleated giant cells- fusions of several activated Mo.
*granulomatous inflammation = sheets
*granuloma = the same cells but organized into masses or nodules.
2.Non-granulomatous inflammation: predominant cell types are lymphocytes and plasma cells
-must reference them by their cell types (ie.lymphoplasmacytic..etc) |
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Term
| Healing and Repair: Regeneration |
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Definition
-healing begins almost immediately after tissue damage occurs
-regeneration = the proliferation of cells and tissues to replace lost or damaged tissues
-results in the complete reconsitution of the tissue
-3 categories of cells and their ability to regenerate:
1.labile cells: normally divide continuously as part of the normal process (Ie, epithelial cells, lymphoid cells, hematopoietic cells)
2.stable cells: do not normally divide but can under certain circumstances (ie the liver and kidney)
*conditions for regeneration:
a.precursor cells remain
b.adequate blood supply remain
c.basement membrane remains
d.viable cnnective tissue for scaffolding
e.duct system to remove secretions of glandular origin
3.Permanent cells: cannot regenerate (ie. neurons, skeletal and cardiac myocytes) |
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Term
| Healing and Repair: Repair |
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Definition
-occurs when the original tissue cannot regenerate and involves replacement of the damaged tissue with fibrous connective tissue (collagen).
-can restore some original structure but may result in a loss of function.
-24 hours after injury, fibroblasts and vascular endothelial cells begin proliferating to form GRANULATION TISSUE
-repair or replacement involves the following steps:
1.angiogenesis
2.migration and proliferation of fibroblasts
3.deposition of ECM
4.maturation and organization of the fibrous tissue = remodelling
-2 types of healing occur depending on the nature, size and cleanliness
1.healing by primary union- minor damage
2.healing by secondary union- extensive damage |
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Term
| Healing and Repair: Repair (Primary union/first intention) |
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Definition
-occurs with minor damage such as a surgical incision provided the edges are closely opposed and there is no infection.
-least complicated and with minimal scarring
-Sequence of events:
1.(within 24 hours):
a.blood clot fill the wound
b.No migrate to the wound
c.hyperplasia of the epidermal cells near the wound
2.(2-7 days)
a.Mo begin blood clot removal, and fibroblasts begin replacing the fibrin in the clot with collagen
b.early capillaries appear =beginning of granulation tissue
c.epidermal cell migrate to establish continuity
3.(weeks)
a.maturation of new BV's and fibrblasts = late granulation tissue
b. wound space is filled with mature collagen |
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Term
| Healing and Repair:Repair (secondary union/second intention) |
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Definition
-occurs in severe damage
-all inflammation must be gone before this occurs
-dependent on the formation of granulation tissue
**over production of granulation tissue in horses = "proud flesh"
-immature granulation tissue is composed of:
1.residual Mo and other imflammatory cells
2.new capillary beds (neovascularization)
3.activated fibroblasts which secrete ECM. collagen synthesis occurs after 1 week.
*initially type 3 collagen is layed down and matures to type 1
-Granulation tissue maturation and the final stages of repair involve:
1.BV and endothelial cell maturation with decreased edema
2.cellular reorientation, with vessles aligned to travel along the surface of the wound and collagen aligned perpendicular to this.
3.aggregation of collagen to form parallel fibers
4.remodelling of collagen into dense bands
5.wound contraction |
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Term
| Healing and Repair:The Extracellular matrix (ECM) |
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Definition
-composed of:
1.fibrous structural proteins
2.adhesive glycoproteins
3.gel-like prteoglycans
-as wounds repair they attempt to re-establish the ECM.
-the following are synthesized by mesenchymal cells:
a.proteoglycans: mucopolysaccharides which sequester water in order to provide organization. they are the first to form in wound healing
b.elastic fibers: similar in structure to collagen but with fexer cross-links. They form random coils and are not organized.
c.fibronectin:an adhesive glycoprotein present in tissue and plasma that functions as the glue between all the ECM constituents. It is also a chemotactic factor for Mo and fibroblasts
d.collagen: gives tensile strength to normal and scar tissue and is composed of 3 alpha subunits which form a helix.
*there are 2 categories of collagen:
1.fibrillar (interstitial)
2.non-fibrillar (amorphous)
*there are 6 types of collagen (1-6) where type 1 and type 3 are the most important. (both are fibrillar) |
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