2Ways of Repairing Tissue Tissue repair depends on the type of tissue damaged and the severity of the injury.Regeneration: replacement of destroyed tissue with the same kind of tissue.Fibrosis: involves the proliferation of fibrous connective tissue often called scar tissue.
3Tissue Repair has 3 steps InflammationOrganizationTwo possiblities:RegenerationFibrosis
4Step 1: InflammationTrauma causes injured cells to release inflammatory chemicals that cause capillaries to dilate.Capillaries become permeable releasing antibodies and clotting proteins that stop the loss of blood and walls in the wound.The walled in wound is isolated from other tissuesThe area of the clot exposed to the air forms a scab
6Step 2: OrganizationDuring this phase the blood clot is replaced by granulation tissueGranulation tissue is a delicate pink tissue composed of a network of capillariesCapillaries are fragile and bleed freely which is demonstrated when someone picks a scabFibroblasts and collagen fibers bridge the gap and have contractile properties that pull the wound together.Macrophages digest the original blood clot
8Step 3: If Regeneration… In pure infections (a pimple or sore throat) healing = regeneration.During organization the surface epithelium begins to regenerate growing under the scab. The scab eventually detaches.The scar may be invisible or visible as a thin white line, depending on the severity of the wound.
9Step 3: If Fibrosis…Destructive/severe infections lead to scarring/fibrosis.Granulation tissue becomes a permanent fibrous tissue patch (scar tissue) that is resistant to infectionOver months the fibrous mass becomes smaller and compact. The scar appears pale and shiny, made of collagen fibers.
11Step 3: If Fibrosis…It is strong but lacks flexibility and elasticity. It cannot perform the normal functions of the tissue it replaced.Scar tissues create blockages in the heart, hampers the muscle’s ability to expand and contract.It causes adhesions in abdominal surgery. The adhesions prevent the normal shifting of loops of the intestines causing obstructions.They can also immobilize joints when adhesions exist in connective tissue.
12Capability of regeneration according to tissue: TISSUE TYPECapacity to regenerateEpithelialVery goodBoneLoose Connective Tissue (Areolar)Blood Forming tissueSmooth muscleModerate
13Capability of regeneration according to tissue: TISSUE TYPECapacity to regenerateDense regular connective tissue (tendon)Moderate to weakSkeletal muscleWeakCartilageCardiac muscleNone (becomes scar tissue)Nervous tissue in the brainSpinal cord