Wound Healing Types:
– Occurring when a wound is closed within a few hours of its creation.
Wound edges are surgically or mechanically approximated, and collagen
metabolism provides long-term strength.
Healing – Occurs when a poorly delineated wound is left open to protect
against wound infection. The open wound allows for the natural host
defense to debride the wound before closure.
– Occurs when an open full thickness wound is allowed to close by wound
contraction and epithelialization.
Partial-Thickness Wounds – Occurs when a partial-thickness wound is
closed primarily by epithelialization. This wound healing involves the
superficial portion of the dermis. There is minimal collagen deposition,
and an absence of wound contraction.
Phases Of Wound
trapped for essential hemostasis
Alpha granules of
the platelets produce growth factors (PDGF, TGF-b, Platelet factor IV),
which initiate the wound healing cascade by attracting and activating
fibroblasts, endothelial cells, and macrophages.
Dense bodies of
the platelets store vasoactive amines (serotonin) which increase vascular
from factor I (Fibrinogen), essential for early wound healing because it
provides the matrix into which cells can migrate.
wound with granulocytes (24-48 hours of the injury). This occurs through
chemotaxis by the release of chemical messengers from platelets. The major
function of granulocytes is to remove bacteria and foreign debris from the
monocytes (wound macrophages) (48-72 hours of injury). These cell are
phagocytic and are the primary producer of the growth factors responsible
for proliferation of extracellular matrix, smooth muscle, and endothelial
cells resulting in angiogenisis. These cells occur through chemotaxis by
attractants such as complements, IgG fragments, collagen, cytokines,
platelet factor IV, and platelet growth factors (PDGF & TGF-b).
mesenchymal cells into the wound.
synthesis. Collagen provides strength and integrity for all tissues.
I – structural component of bones, skin, and tendons
II – structural component of cartilage
III – found in association with Type I
IV – structural component of basement membrane
V – found in the cornea.
Formation of new
blood vessels. This process is initiated by TGF-b and other growth
factors, and is ongoing throughout the wound healing phases.
differentiated epithelium which provides a barrier between internal and
synthesis and breakdown, remodeling the extracellular matrix.
granulocytes, and macrophages produce metalloproteinases which is needed
for collagen degradation.
inhibitors are produced by TGF-b which underlie the ability to promote