wound healing 3

8/13/2019 Wound Healing 3

1/34

Irzan Gustanto


2/34

THE RESPONSE TO INJURYWound healing : the repair or reconstitution of a

defect in an organ or tissue

Inflammatoryphase, proliferative phase, remodelingphase


3/34

PHASES OF NORMAL

WOUND HEALING Inflammatory Phase

Proliferative Phase

Remodeling Phase


4/34


5/34

Inflammation is the first stage of wound healing

Hemostasis

Removal of dead and devitalized tissues

prevention of colonization and invasive infectionby microbial pathogens, principally bacteria.

Platelets aggregate and form the initialhemostatic plug

The coagulation and complement cascades areinitiated


6/34

Intrinsic and extrinsic coagulation

cascades is the conversion of fibrinogen tofibrin and subsequent polymerization intoa gel-> fibrin matrix

There is neutrophilic infiltrate into thefibrin matrix filling the wound cavity. Roleof these cells:

to remove dead tissue by phagocytosis and to prevent infection by oxygen-dependent

and independent killing mechanisms.


7/34

INFLAMMATORY PHASE


8/34

Monocyte/macrophages followneutrophils into the wound and appear 48to 72 hours after injury

By the third day after wounding they arethe predominant cell type in the healingwound,

Phagocytose debris and bacteria,

Critical for orchestrated production of growth factorsnecessary for production of the extracellular matrixby fibroblasts and the production of new blood

vessels in the healing wound


9/34

Macrophages role, Phagocytose debris and bacteria,

Critical for orchestrated production of growth factorsnecessary for production of the extracellular matrix

by fibroblasts and the production of new bloodvessels in the healing wound

These peptide growth factors activate and

attract local endothelial cells, fibroblasts,and keratinocytes to begin their respectiverepair functions


10/34


11/34

Occurring from days 4 to 21 following injury

Keratinocyte migrate to restore epithelial continuity Platelets, macrophages,and local ECMgrowth factorinitiate fibroblast activation

Fibroblast migrate into the woundactivated

increase protein synthesis

cell division The provisional fibrin matrix is gradually replaced by a

new platform for migration: granulation tissue


12/34


13/34


14/34

Granulation tissue begins to appear in human

wounds by about day 4 postinjury Fibroblasts produce the extracellular matrix

that fills the healing scar and provides aplatform for keratinocyte migration

Macrophages produce growth factors(PDGF,TGF-1) that induce fibroblasts toproliferate, migrate, and deposit extracellularmatrix, as well as stimulating endothelial cellsto form new vessels


15/34

Contraction is the process in which thesurrounding skin is pulledcircumferentially toward the wound

Open wounds are characterized

Occur after trauma, burns or when

previously closed wounds are secondarilyopened cause infection

Wound contractiondecreases the sizeof the woundwithout new tissueformation


16/34


17/34

Clinically, wound contraction can lead tocontracture,

which distorts tissue and leads todecreased function


18/34

The process of epithelial renewal after injury.

Particularly important in partial thicknessinjuries, but plays a role in all healing.

Partial thickness wounds have epidermis anddermis damaged, with some dermis preserved.Epithelial cells involved in healing come from

wound edges and sweat glands, sebaceousglands in the more central portion of wound.


19/34

Within hours after injury, morphologic changesin keratinocytes at the wound margin are

evident Epidermis thickens, marginal basal cell enlarge

and migrate over the wound defect

epithelial cells begin migrating, they do notdivide until epidermal continuity is restored.

New epithelial cells for wound closure areprovided by fixed basal cells in a zone near the

edge of the wound


20/34

In humans is believed to last from 21 daysup to 1 year.

Rate increases rapidly, and continues at arapid rate for 2-4 weeks in most wounds.

As more collagen is synthesized, itgradually replaces fibrin as the primarymatrix in the wound.


21/34

Reorganization of previously synthesizedcollagen

Collagen is broken down by matrixmetalloproteinase, and the net woundcollagen content is the result of balancebetween collagenolysis and collagensynthesis


22/34

The number of intra and intermolecularcross-links between collagen fibers

increases dramatically.Once collagen matrix has filled in thewound cavity, fibroblasts rapidly disappear

and newly formed blood regressA major contributor to the increase inwound strength. Remodeling continues for12 month, so scar revision should not be

done prematurely.


23/34

At 3 weeks, the beginning of theremodeling phase, wounds only haveapproximately 20% of the strength ofunwounded skin,

Eventually only possess 70% of the

breaking strength of unwounded skin.


24/34

The final result of tissue repair is scar,which is brittle, less elastic than normalskin, and does not contain any skinappendages such as hair follicles or sweatglands.

The major benefit of repair by scar is therelatively rapid reformation of tissueintegrity


25/34


26/34


27/34


28/34


29/34

Primary

Secondary


30/34

Primary intention healing occurs in closedwounds, which are wounds with the edgesapproximated

Uncomplicated wounds healing with primaryintention epithelialize within 24-48 h


31/34

Open wounds heal with the same basic processes

of inflammation, proliferation, and remodeling asclosed wounds

The major difference is that each sequence is

much longer, especially the proliferative phase.There is much more granulation tissue formationand contraction


32/34


33/34


34/34

wound healing 3

Documents