Wound Healing – B. Pharma 2nd Semester Pathophysiology notes pdf




       Process of

       Healing by
first intention

       Healing by
second intention

of wounds


At the end of this PDF, student will be able to

         Define “Healing”

        Describe the processes involved in healing

        Describe the contraction of wound

        Explain the process of healing of wound of


Wound Healing


       Healing – body response to injury

       An attempt to restore normal structure and function

       Involves 2 distinct processes:

       Regeneration – healing by proliferation of parenchymal cells ;
results in complete restoration

       Repair – healing by proliferation of connective tissue elements
resulting in fibrosis and scar


       Proliferation of parenchmal cells

       Complete restoration of original tissue

       Cells are under the constant regulatory control of their cell cycle


       Epidermal growth factor

       fibroblast growth factor,
platelet derived

      growth factor, endothelial growth factor,

      transforming growth factor-β

Cell cycle and its phases

       Period between two successive cell divisions

       M (mitosis) phase: Phase of mitosis.

       G1 (gap 1) phase: daughter cell enters G1 phase after mitosis

       S (synthesis) phase: the synthesis of nuclear DNA

       G2 (gap 2) phase

       G0 (gap 0) phase: resting phase of the cell after an M phase

Phases of cell cycle

Type of cells involved
in regeneration –
depending on the speed of cell division

       Labile cells – continuously dividing

       Epidermis, mucosal epithelium, GI tract
epithelium etc

       Stable cells – low level of replication

       Hepatocytes, renal tubular epithelium, pancreatic

       Permanent cells – never divide

       Nerve cells, cardiac myocytes, skeletal muscle

Tissue Repair

       Replacement of injured tissue by fibrous tissue

Two processes are involved in repair:

1. Granulation tissue formation

2. Contraction of wounds

       Involves mesenchymal cells

       connective tissue cells

       endothelial cells, macrophages & some
parenchymal cells

Granulation tissue formation

Phase of inflammation

       Acute inflammatory

       Response with exudation of plasma, neutrophils

       Monocytes within 24 hours

Phase of clearance

       Proteolytic enzymes liberated from Neutrophils

       Autolytic enzymes from dead tissues cells

       Phagocytic activity of macrophages

       Clear off the necrotic tissue, debris and RBCs

Phase of ingrowth of granulation tissue


Proliferation of endothelial

of capillary sprout

Vascular endothelial growth
factor (VEGF)

Platelet-derived growth factor

2. Fibrogenesis

Fibroblasts originate from

Collagen fibrils begin to
appear by about 6th day

Formation of inactive looking
scar – cicatrisation

Contraction of wounds

       Wound starts contracting after 2-3 days

       Process is completed by the 14th day

       Reduced by approximately 80% of its original size

       Results in rapid healing


       Contraction of collagen

       Appearance of Myofibroblasts

Healing of wound in skin

       Combination of Regeneration and repair

Accomplished in one of the following two

Ø  Healing by first intention (primary union)

Ø  Healing by second intention (secondary union)

Healing by first intention (primary union)


       Clean and uninfected

       Surgically incised

       Without much loss of cells and tissue

       Edges of wound are approximated by surgical sutures

Sequence of events

       Initial haemorrhage

       Acute inflammatory response

       Epithelial changes


       Suture tracks

Healing by first intention

Healing by second intention (secondary union)


       Open with a large tissue defect, at times infected

       Having extensive loss of cells and tissues

       The wound is not approximated by surgical sutures but is left open

Sequence of events

       Initial haemorrhage followed by clotting

       Inflammatory phase – neutrophills & macrophages

       Epithelial changes – epidermal cell margination & proliferation

       Granulation tissue

       Wound contraction

Factors affecting wound healing

Local factors


       Blood supply to wound area

       Mechanical factors

       Foreign bodies

       Exposure to ionising radiation

       Size, Location & type of wound

Systemic factors



       Systemic infection

       Uncontrolled diabetes

       Haemetological abnormalities


       Healing is a body response to injury it is an  attempt to restore normal structure and

       Healing occurs by two processes- regeneration
and repair

       Contraction of wound involves dehydration, contraction of collagen,
appearance of myofibroblasts

       Healing of wounds of skin occurs by first
intention or second intention depending on the type of infection

Leave a comment