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.
1.
2.
3.
Inflammation
Organization
Two possiblities:


Regeneration
Fibrosis
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


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
http://drwheatgrass.com/conditions/woundhe
aling/skingraft2.htm#f5



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.



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.
http://drwheatgrass.com/conditions/woundhe
aling/skingraft2.htm#f5

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.
TISSUE TYPE
Epithelial
Capacity to
regenerate
Very good
Bone
Very good
Loose Connective Tissue
(Areolar)
Blood Forming tissue
Very good
Smooth muscle
Moderate
Very good
TISSUE TYPE
Capacity to regenerate
Dense regular connective tissue
(tendon)
Skeletal muscle
Moderate to weak
Cartilage
Weak
Cardiac muscle
None (becomes scar
tissue)
None (becomes scar
tissue)
None (becomes scar
tissue)
Nervous tissue in the brain
Spinal cord
Weak