Repair and healing

1. REPAIR AND HEALING
Nursing 2nd Year,
Class III

2. • Wound is a break in the integrity of skin or
tissues; associated with disruption and
function.

3. • Injury to tissue may result in cell death &
destruction
• The inflammatory response to microbes and
injured tissues not only serves to eliminate
these dangers, but also sets into motion the
process of repair.
• Healing is an attempt to restore the normal
structure and function

4. What is Repair????
• Repair or healing refers to the restoration of
tissue architecture and function after an
injury.

5. • Repair of damaged tissues occurs by two types
of reactions:
1. Regeneration by proliferation of residual
(uninjured) cells and maturation of tissue
stem cells
2. Deposition of connective tissue to form a scar

6. REGENERATION
• Some tissues are able to replace the damaged
components and essentially return to a
normal state
• Occurs by proliferation of cells that survive the
injury and retain the capacity to proliferate

7. Connective tissue deposition (scar
formation)
• If the injured tissues are incapable of
complete restitution, or if the supporting
structures of the tissue are severely damaged,
repair occurs by the laying down of connective
(fibrous) tissue SCAR

8. • Types of cells on the basis of regeneration
capacity—
1. Labile cells(continuous proliferation
throughout life) Bone marrow cells, cells
lining skin, GIT, transitional cell of bladder
2. Stable cell(undergo replication only when
stimulated) Liver, renal tubules,
chondroblasts, osteoblasts
3. Permanent cells( do not replicate after
birth) Neurons, skeletal muscle, cardiac
muscle cells

9. STEPS IN SCAR FORMATION
• Angiogenesis/Neovascularisation.
• Formation of granulation tissue.
• Remodelling of connective tissue

10. ANGIOGENESIS(NEOVASCULARISATION)
• Formation of new blood vessels, which supply
nutrients and oxygen needed to support the
repair process.
• New vessels sprout from the parent vessels
and migrates towards the area of damage.

11. STEPS IN ANGIOGENESIS
• Vasodilation and increased permeability
• Separation of pericytes from the abluminal
surface and breakdown of the basement
membrane to allow formation of a vessel
sprout
• Migration of endothelial cells toward the area
of tissue injury

12. • Proliferation of endothelial cells just behind
the leading front of migrating cells
• Recruitment of periendothelial cells (pericytes
for small capillaries and smooth muscle cells
for larger vessels) to form the mature vessel
• Suppression of endothelial proliferation and
migration and deposition of the basement
membrane.

13. ANGIOGENESIS

14. GRANULATION TISSUE FORMATION
• Migration and proliferation of fibroblasts and
deposition of loose connective tissue,
together with the vessels and interspersed
leukocytes granulation tissue

15. CONNECTIVE TISSUE REMODELLING
• Maturation and reorganization of the
connective tissue (remodeling) stable
fibrous scar

16. DEPOSITION OF CONNECTIVE TISSUE
• The laying down of connective tissue occurs in
two steps:
1. Migration and proliferation of fibroblasts
into the site of injury.
2. Deposition of ECM proteins produced by
these cells

17. FACTORS INFLEUNCING TISSUE REPAIR
• Infection
• Diabetes
• Nutritional status
• Foreign bodies
• Mechanical factors
• Type and extent of tissue injury
• Location of injury

18. HEALING OF SKIN
WOUNDS(Involves both epithelial
regeneration and the formation
of connective tissue scar)

19. HEALING BY FIRST INTENTION
• Injury involving only the epithelial layer.
• The incision causes only focal disruption of
epithelial basement membrane continuity and
death of relatively few epithelial and
connective tissue cells

20. • Wounding causes the rapid activation of
coagulation pathwaysblood clot on the
wound surface .
• The clot serves to stop bleeding .
• As dehydration occurs at the external surface
of the clot, a scab covering the wound is
formed.

21. FIRST 24 HOURS
• Neutrophils are seen at the incision margin,
migrating toward the fibrin clot.
• They release proteolytic enzymes that begin
to clear the debris.
• Basal cells at the cut edge of the epidermis
begin to show increased mitotic activity.

22. 24 to 48 HOURS
• Epithelial cells from both edges have begun to
migrate and proliferate along the dermis,
depositing basement membrane components
as they progress.
• The cells meet in the midline beneath the
surface scab, yielding a thin but continuous
epithelial layer that closes the wound.

23. BY DAY 3
• Neutrophils have been largely replaced by
macrophages, and granulation tissue
progressively invades the incision space.
• Collagen fibers are now evident at the incision
margins.
• Epithelial cell proliferation continues, forming
a covering approaching the normal thickness
of the epidermis

24. DAY 5
• Neovascularization reaches its peak as
granulation tissue fills the incisional space.
• The fibroblasts produce ECM proteins and
collagen fibrils become more abundant and
begin to bridge the incision.
• The epidermis recovers its normal thickness as
differentiation of surface cells yields a mature
epidermal architecture with surface
keratinization.

25. SECOND WEEK
• Continuous collagen accumulation and
fibroblast proliferation.

26. END OF FIRST MONTH
• Scar comprises a cellular connective tissue
largely devoid of inflammatory cells and
covered by an essentially normal epidermis.
• However, the dermal appendages destroyed in
the line of the incision are permanently lost.
• The tensile strength of the wound increases
with time.

27. HEALING BY SECOND INTENTION
(SECONDARY UNION)
• When cell or tissue loss is more extensive,
such as in large wounds, abscesses, ulceration,
and ischemic necrosis in parenchymal organs,
the repair process involves a combination of
regeneration and scarring.

28. • Inflammatory reaction is more intense, there
is development of abundant granulation
tissue, accumulation of ECM and formation of
a large scar and wound contraction by the
action of myofibroblasts.

31. THANK YOU