71
issue repair, which overlaps the inflammatory pro-
cess that was discussed in Chapter 3, refers to the
restoration of tissue structure and function after an
injury. Tissue repair can take the form of regeneration,
in which injured cells are replaced with cells of the same
type, sometimes leaving no residual trace of previous
injury; or it can take the form of replacement by con-
nective (fibrous) tissue, which leads to scar formation
or fibrosis in organs such as the liver or lung. For many
types of common injuries, both regeneration and con-
nective tissue replacement contribute to tissue repair.
This chapter is divided into two parts. The first part dis-
cusses cell proliferation and regeneration, the cell cycle,
the role of stem cells, growth factors, and the extracel-
lular matrix in tissue renewal. The second focuses on
connective tissue repair, cutaneous wound healing, fac-
tors that affect wound healing, and the effect of aging
on wound healing.
Cell Proliferation andTissue
Regeneration
Tissue repair involves the proliferation of various cells,
and close interactions between cells and the extracel-
lular matrix (ECM). Body organs and tissues are com-
posed of two types of tissues: parenchymal and stromal.
The parenchymal tissues consist of the functioning cells
of an organ or body part: whereas, the stromal tissues
contain the supporting connective tissues, blood vessels,
fibroblasts, nerve fibers, and extracellular matrix.
Cell Proliferation Versus
Differentiation
Cell proliferation
refers to the process of increasing
cell numbers by mitotic division.
Cell differentiation
is
the process whereby a cell becomes more specialized in
T
Cell Proliferation
and Tissue
Regeneration
and Repair
4
C h a p t e r
Cell Proliferation and Tissue Regeneration
Cell Proliferation Versus Differentiation
The Cell Cycle
Proliferative Capacity of Tissues
Stem Cells
Influence of Growth Factors
Extracellular Matrix and Cell–Matrix Interactions
Healing by Connective Tissue Repair
Phases of Repair
Angiogenesis and Ingrowth of Granulation
Tissue
Emigration of Fibroblasts and Deposition of
Extracellular Matrix
Maturation and Remodeling of the Fibrous
Tissue
Cutaneous Wound Healing
Healing by Primary and Secondary Intention
Phases of Healing
Factors That Affect Wound Healing
Nutritional Status
Blood Flow and Oxygen Delivery
Impaired Inflammatory and Immune Responses
Infection, Wound Separation, and Foreign
Bodies
Wound Healing in the Elderly
