Download - Tissue Repair
Tissue Repair
Ways of Repairing TissueTissue 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.
Tissue Repair has 3 steps1. Inflammation2. Organization3. Two possiblities:
Regeneration Fibrosis
Step 1: Inflammation
Trauma 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 tissues
The area of the clot exposed to the air forms a scab
Step 2: Organization During this phase the blood clot is replaced
by granulation tissue Granulation tissue is a delicate pink tissue
composed of a network of capillaries Capillaries are fragile and bleed freely which
is demonstrated when someone picks a scab
Fibroblasts and collagen fibers bridge the gap and have contractile properties that pull the wound together.
Macrophages digest the original blood clot
Granulation Tissue
http://drwheatgrass.com/conditions/woundhealing/skingraft2.htm#f5
Step 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.
Step 3: If Fibrosis…
Destructive/severe infections lead to scarring/fibrosis.
Granulation tissue becomes a permanent fibrous tissue patch (scar tissue) that is resistant to infection
Over months the fibrous mass becomes smaller and compact. The scar appears pale and shiny, made of collagen fibers.
Scar after fibrosis
http://drwheatgrass.com/conditions/woundhealing/skingraft2.htm#f5
Step 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.
Capability of regeneration according to tissue:
TISSUE TYPE Capacity to regenerate
Epithelial Very good
Bone Very good
Loose Connective Tissue (Areolar)
Very good
Blood Forming tissue Very good
Smooth muscle Moderate
Capability of regeneration according to tissue:
TISSUE TYPE Capacity to regenerateDense regular connective tissue (tendon)
Moderate to weak
Skeletal muscle Weak
Cartilage Weak
Cardiac muscle None (becomes scar tissue)
Nervous tissue in the brain None (becomes scar tissue)
Spinal cord None (becomes scar tissue)