Cellular adaptation:
Atrophy
Hypertrophy
Hyperplasia
Metaplasia
Chapter Two Tissue injury
CELLULAR ADAPTATION
? Excessive physiologic stresses.
? Some pathologic stimuli.
A new,but altered state preserving
the viability of the cell.
ATROPHY
Decrease in mass of the cell
HYPERTROPHY
Increase in mass of the cell
ATROPHY
? Decreased workload.
? Loss of innervation.
? Diminished blood supply.
? Inadequate nutrition.
? Loss of endocrine stimulation.
? Aging
Morphology of atrophy
Brown atrophy
Reduction in the number of cell
organelles.
Increase in the number of autophagic
vacuoles.
Lipofuscin granules (Brown atrophy)
Fig 2-5
HYPERTROPHY
? Increased functional demand.
? Specific hormonal stimulation.
Fig 2-6
HYPERPLASIA
The myth of Prometheus.
HYPERPLASIA
? Physiologic hyperplasia:
Hormonal hyperplasia
Compensatory hyperplasia
? Pathologic hyperplasia:
Excessive hormonal stimulation.
Effects of locally produced GFs on target cells,
? Fig 2-1
PARTIAL HEPATECTOMY
Priming
Proliferation
Groeth lnhibition
GROWTH FACTORS
AND CYTOKINES
HGF
TGF-?
EGF
TNF-?
IL-6
Others
ADJUVANTS
Norepinephrine
Insulin
Glucagon
Thyroid hormone
GROWTH INHIBITORS
TGF-?
Others
Growth factors
Adjuvanis
Matrix degradation
Metaplasia
? One adult cell type is replaced by
another.
? Genetic reprogramming of stem
cells.
? Epithelial and mesenchymal
metaplasia.
? Squamous metaplasia
Bronchial epithelia
Epithelia in bile duct
Cervical epithelia
? Intestinal metaplasia of gastric epithelia
? Bone metaplasia.