Repair and Healing

8/6/2019 Repair and Healing

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At the end of this lecture, student shouldbe able to:


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The healing process occur depend on type of cells

and organ involved during injury. Cells can be divided into 3 major groups;

i. Labile (continuous dividing) e.g. epithelial & blood cells.

ii. Stable (low level of replication; decrease or losetheir ability to proliferate after adolescence) e.g.fibroblast, smooth muscle cells, bone & cartilagecells

iii. Permanent (never divide) e.g. nerve cells, cardiacmyocytes.

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2 processes:(i) Granulation tissue formation(ii)Contraction of wounds

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3 phases :(a) PHASE OF INFLAMMATION

trauma, blood clots (site of injury)acute response :exudation of plasma,neutrophils, monocytes ( 24 hours)

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(c) PHASE OF INGROWTH OF GRANULATION2 main processes:

i. Angiogenesis (neovascularisation)formation of new blood vessels

ii. Fibrogenesis

formation of fibrocytes and mitoticdivision by fibroblasts; myofibroblastsIn 6 th days, more collagen is formed

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Start after 2 -3 days; completed: 1 4 th day Wound reduced 80% of its original size Contraction occur: rapid healing

process Factors under mechanism of wound

contraction:(a) dehydration(b) contraction of collagen(c) myofibroblasts

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1. Healing by first intention (Primary union)characteristics:- clean & uninfected- surgical incised- without much loss of cells & tissue- edges of wound surgical sutures

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2 . Healing by second intention (Secondaryunion)

Characteristics:- Large tissue defect- extensive loss of cells & tissues

- not approximated by surgical suturesbut left open

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5 stages of healing (primary Union);i. Initial Haemorrhageii. Acute Inflammation responseiii. Epithelial changesiv. Organization v. Suture tracks

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6 stages of healing (secondary Union);i. Initial Hemorrhageii. Inflammation phaseiii. Epithelial changesiv. Granulation tissue v. Wound contraction vi. Presence of infection

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Repair ; regeneration of injured tissue by parenchymal cells of the same type.

Replacement by connective tissue occur whenrepair by parenchymal regeneration alone cannot be accomplished.

Involves production of Granulation tissue . Replacement of parenchymal cells with

proliferating fibroblasts & vascular endothelialcells .

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Factors affecting healing;i. Systemic e.g. age, nutrition, immune

status.ii. Local e.g. infection, blood supply,

mobility, foreign body.

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"Each time you are honest and conduct yourself with honesty, a success force will

drive you toward greater success. Each time you lie, even with a little white lie,

there are strong forces pushing you toward failure."

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THANK YOU

FOR YOUR ATT E NTI O N

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Repair and Healing

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