4. cellular adaptations mdzah- sp sinhasan
TRANSCRIPT
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1. Atrophy (decrease in cell size)
2. Hypertrophy (increase in cell size)
3. Hyperplasia (increase in cell number)
4. Metaplasia (change in cell type)
5. Dysplasia (disordered arrangement)
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Physiologic: Developmental – e.g.. Thyroglossal duct
Uterus following parturition
Pathologic: Decreased workload – Disuse atrophy
Loss of innervations – Denervation atrophy
Decreased blood supply – Brain atrophy
Malnutrition – Marasmus.
Loss of endocrine support – endocrine glands.
Ageing: Senile atrophy
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Normal
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Hypertrophy is an increase in cell size by gain of
cellular substance
With the involvement of a sufficient number of cells,
an entire organ can become hypertrophic
Caused by:
Increased functional demand or
Specific endocrine stimulations
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Hypertrophy….,
Not only the size, but also the phenotype of individual
cells can be altered in hypertrophy
With increasing demand, hypertrophy can reach a
limit beyond which degenerative changes and organ
failure can occur
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Increase in the number of indigenous cells in an organ or tissue
Pathological hyperplasia if typically the result of excessive endocrine stimulation
Hyperplasia is often a predisposing condition to neoplasia
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NORMALHYPERPLASTIC
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Metaplasia is a “reversible” change in which one adult cell type is replaced by another adult cell type.
Metaplasia is a cellular adaptation in which
indigenous cells are replaced by cells that are better suited to tolerate a specific abnormal environment
Because of metaplasia, normal protective
mechanisms may be lost: Persistence of signals that result in metaplasia often lead to neoplasia.
Metaplasia
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E.g. Cervical dysplasia
Dysplasia is a step toward cancer.
Dysplasias may progress to malignant neoplasms
“Cells having disordered arrangement”
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In areas of necrosis,
In atheromas,
In Damaged heart valves,
In tuberculous Lymph-node.
Grossly: Appear as fine white granules or clumps felt as gritty deposits.
Microscopically: basophilic amorphous granular, clumped appearance.
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Metastatic calcification is calcium deposition in
normal tissues as a consequence of hypercalcemia:
– Increased PTH
– Bone destruction
– Vitamin D disorders (intoxication, Sarcoidosis)
– Renal failure
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