Section 3
Wound healing
1. Definition:
Refers to the body’s replacement
of destroyed tissue by living tissue
2. Stages in healing of wound
(1) Escape of blood and exudates
(2) Acute inflammation
(3) Contraction of the wound. The
causes of contraction are not known
but possible mechanisms are:
① Shrinkage of scab in superficial wounds
② Contraction properties of granulation
tissue attributable to contraction of
myofibroblasts or tissue re-modeling.
( 4 ) Proliferation and migration of
fibroblasts and endothelial cells.
(5) Progressive increase in mature
collagen fibres during the second
week forming a scar.
(6) Loss vascularity and shrinkage of
the scar.
3. Type of wound healing
(1) Healing by fist intention
A clean wound with a
minimum of space between the
margins.
healing by first intention
(参照武忠弼 病理学，1998 修改 )
(2) Healing by second intention
Healing by second intention differs
from healing by first intention in:
① Greater tissue loss
② More inflammatory exudates and
necrotic material to remove
③ More granulation tissue therefore a
bigger scar
healing by second intention
(参照武忠弼 病理学，1998 修改 )
④ Wound contraction necessary
⑤ Slower process
⑥ Increased liability to infection
(3) Healing under scab
4. Factors influencing wound healing
(1) Local factors adversely affecting healing
① Type of wounding agent; blunt, crushing,
tearing etc.
② Infection
③ Foreign bodies in wound
④ Poor blood supply
⑤ Excessive movement
⑥ Poor apposition of margins, e. g.
large haematoma formation
⑦ Poor wound contraction due to
tissue tethering
⑧ Infiltration by tumor.
⑨ Previous irradiation.
(2) General factors adversely affecting
healing
① Age
② Poor nutrition
Deficiency of protein
Lack of Vitamin C results in abnormal
granulation tissue and deficient collagen
production
Zinc deficiency
③ Excessive glucocorticosteroid
production or administration
④ Fall in temperature
⑤ Jaundice
(3) Factors accelerating wound
healing
① Ultraviolet light.
② Administration of anabolic steroids,
deoxycorticosterone acetate, cell
growth factors.
③ Rise in temperature.