CELLULAR ADAPTATIONS.ppt An introduction

An introduction to Cellular Adaptations

1. CELLULAR ADAPTATIONS
Dr. J. Karthikesh MD

2. Atrophy
It is a defined as reduction in the number and
size of cells and organs which was once
normal.

3. Causes
Physiological causes
–Normal process in aging. Eg.Lymph node,
appendix, thymus
–Atrophy of gonads after menopause
–Atrophy of brain

4. Pathological atrophy
Starvation
Ischemic atrophy
Renal atrophy in atherosclerosis of renal artery
Disuse atrophy
–Limbs in Casts
–Pancreatic atrophy in duct obstruction
Neuropathic atrophy
- Poliomyelitis
- Motor neuron disease
- Nerve section

5. Pathological atrophy
Endocrine atrophy
–Hypopituitarism leads to atrophy of adrenal and
gonads
–Hypothyroidism leads to atrophy of skin
Pressure atrophy
Erosion of spine, cranium, sternum by tumors
Idiopathic atrophy
- Myopathies
- Testicular atrophy

6. Hypertrophy
Increase in the size of the cells leading to
increase in the size of the organ without
increase in number of cells.

7. Causes
Physiological
–Enlargement of uterus in pregnancy.

8. Causes
Pathological
–Cardiac muscle hypertrophy in
Systemic hypertension
Aortic valve disease
Mitral insufficiency
Smooth muscle hypertrophy in
Cardiac achalasia
Pyloric stenosis
Intestinal strictures

9. Causes
Hypertrophy of skeletal muscle
–Athletes
–Manual labourers
Compensatory hypertrophy
occurs when one of a pair is removed eg. Lungs.

10. Metaplasia
It is a reversible change of one type of
epithelial cell or mesenchymal adult cell to
another type of adult epithelial or mesenchymal
cell, usually in response to abnormal stimulus.
–It USUALLY reverts to normal on removal of the
abnormal stimulus
–However, it may transform into cancer

11. Types of Metaplasia
Epithelial metaplasia
–Common type
–Examples
Squamous metaplasia – Bronchus, Uterine cervix, Gall
bladder, Prostate, Urinary bladder,
Columnar metaplasia – Intestinal metaplasia in gastric
ulcers, Bronchiectasis, Cervical erosions.

12. Types of metaplasia
Mesenchymal metaplasia
–Less common
–Osseous metaplasia
Arterial wall in old age
Myositis ossificans
Cartilage of larynx and bronchi of elderly people
Chronic Scar tissue
Fibrous stroma of tumors

13. DYSPLASIA
It means disordered cellular development often
accompanied by metaplasia and hyperplasia
It is also called as atypical hyperplasia
It is pre-malignant and if untreated will lead to
malignant transformation

14. Characteristics of Dysplasia
Increase in the number of cellular layers
Disorderly arrangement of cells from the basal layer to
the surface layer
Loss of basal polarity – nuclei are away from the
basement membrane
Cellular and nuclear pleomorphism
Increased N:C ratio
Nuclear hyperchromatism
Increased mitoses