CHAPTER 4
CELL PROLIFERATION, TISSUE
REGENERATION AND REPAIR
PRE LECTURE QUIZ
TRUE/FALSE
T
1. Stem cells are undifferentiated cells that have the
capacity to generate multiple cell types.
F
2. DNA synthesis takes place during the G0 phase of the
cell cycle.
T
3. The inflammatory phase of wound healing prepares
the wound environment for the healing process.
T
4. The formation of granulation tissue involves the
creation of new capillaries.
F
5. A large surface wound is likely to heal by the process
of primary intention.
FILL-IN-THE-BLANK
growth
keloids
matrix
Scar
Stable
1. _____________ tissues contain cells that normally stop
dividing when growth ceases.
2. The extracellular _____________ is secreted locally and
assembles into a network of spaces surrounding tissue
cells during the process of tissue regeneration.
3. When regeneration cannot occur, healing by replacement
with a connective tissue occurs, a process that terminates
in ______________ formation.
4. The term _____________ factor is generally applied to
small hormonelike proteins that increase cell size and cell
division.
5. An abnormality in healing by scar tissue repair is the
formation of _____________, which are benign tumorlike
masses caused by excess production of scar tissue.
CELL PROLIFERATION AND TISSUE REGENERATION
Parenchymal tissue
 Stromal tissue

-The working part
- The binding part
CELL PROLIFERATION VERSUS DIFFERENTIATION


Cell proliferation-process of
increasing cell numbers by
mitotic division
Cell Differentiation-process
whereby a cell becomes
more specialized in terms
of structure and function
THE CELL CYCLE

4 distinct phases
PROLIFERATIVE CAPACITY OF TISSUES
Varies with tissue and cell type
3 divisions of body tissues:
a. Continuously doubling
b. Stable
c. Permanent tissues

STEM CELLS
Incompletely differentiated
throughout life
3 Properties:
a.
Self-renewal
b.
Asymmetric replication
c.
Differential potential
(potency)

INFLUENCE OF GROWTH FACTORS


Small hormonelike
proteins that increase
cell size and cell
division
PDGF, FGF, TGF, and
EGF
EXTRACELLULAR MATRIX AND CELL-MATRIX
INTERACTIONS
ECM is secreted locally and assembles a
network of spaces surrounding tissue cells
 Components of ECM:
a. Fibrous structural proteins
b. Water-hydrated gels
c. Adhesive glycoproteins

COMPONENTS OF THE ECM
HEALING BY CONNECTIVE TISSUE REPAIR
PHASES OF REPAIR
Angiogenesis and ingrowth of granulation
tissue
 Emigration of fibroblasts and deposition of
extracellur matrix
 Maturation and reorganization of the fibrous
tissue (remodeling)
Usually begins within 24 hours of injury;
evidenced by the migration of fibroblasts and
the induction of fibroblast and epithelial cell
proliferation

ANGIOGENESIS AND INGROWTH OF
GRANULATION TISSUE
MATURATION AND REMODELING OF THE
FIBROUS TISSUE
CUTANEOUS WOUND HEALING

The transition from granulation to scar tissue
shifts in the modification and remodeling of the
ECM
HEALING BY PRIMARY AND SECONDARY
INTENTION


Primary intention –
sutured surgical incision
Secondary intentionlarger wounds which
have a greater loss of
tissue and
contamination
PHASES OF HEALING
Inflammatory Phase
 Proliferative Phase
 Maturational or Remodeling

KELOIDS
FACTORS THAT AFFECT WOUND HEALING
Nutritional Status
Blood Flow and Oxygen Delivery
Age
NUTRITIONAL STATUS
Local and systemic factors influence wound
healing
 Vitamin C and A play an essential role in the
healing process
 Vitamin C is needed for collagen synthesis
 Vitamin A functions in stimulating and
supporting epitheilial

BLOOD FLOW AND OXYGEN DELIVERY

For healing to occur, wounds must have
adequate blood flow to supply the necessary
nutriients and to remove waste, local toxins,
bacteria and other debris.
WOUND HEALING IN THE ELDERLY
Age-related changes:
A decrease in dermal thickness
A decline in collagen content
Loss of elasticity
 Elderly are more vulnerable to chronic wounds,
such as pressure, diabetic, and ischemic ulcers
as compared to younger persons
