cell injury: cell adaptations
TRANSCRIPT
CELLULAR ADAPTATIONS AND
INJURY
Dr Vijay Shankar S
• Introduction • Cellular adaptations• Types of adaptations • Mechanism • Examples
Pretest
1. In smokers ,the ciliated columnar epithelium of trachea and bronchi are replaced by squamous epithelium. This is an example of
A. Hyperplasia B. Dysplasia C. Metaplasia D. Hypertrophy
• 2. Skin ‘warts’ is an example for A. Hyperplasia B. Dysplasia C. Metaplasia D. Hypertrophy
NORMAL CELL(HOMEOSTASIS)
STRESS
ADAPTATION CELL INJURYINABILITY TO
ADAPT
REVERSIBLE INJURY
MILDTRANSIENT
SEVEREPROGRESSIVE
IRREVERSIBLE INJURY
NECROSIS APOPTOSISCELLDEATH
CELLULAR ADAPTATIONS
ATROPHYHYPERTROPHY HYPERPLASIA
METAPLASIA
• New , steady altered state
• Allows them to survive
• Continue to function
• In abnormal environment
ATROPHY
• Decrease in the number and size of the cells of an organ
• Mechanism :Decreased protein synthesis andincreased protein degradation
in the cells
ATROPHY
PHYSIOLOGICATROPHY
PATHOLOGIC ATROPHY
1. Disuse atrophy
2. Nutritional/starvation atrophy
3. Ischemic atrophy
4. Neuropathic
5. Loss of endocrine stimulation
6. Pressure atrophy
1. Decrease in size of uterus after parturition
2. Brain, with ageing
HYPERTROPHY
• Increase in the SIZE of the parenchymal cells in the organ
• Cause : • Increased functional demand or• By stimulation of hormones and growth factors
• Mechanisms :• Increased production of cellular proteins.
HYPERTROPHY
PHYSIOLOGICHYPERTROPHY
PATHOLOGIC HYPERTROPHY
1. Skeletal muscle
2. Cardiac muscle
3. Smooth muscle
4. Compensatory hypertrophy
1. Enlarged size of the uterus in pregnancy
HYPERPLASIA
• Increase in the NUMBER of cells in an organ
• It takes place if the cell population is capable of dividing
• Mechanism :• Results from growth factor induced proliferation of
mature cells or• Increased output of new cells from stem cells.
HYPERPLASIA
PHYSIOLOGICHYPERPLASIA
PATHOLOGIC HYPERPLASIA
1. Hormonal excess- endometrial, prostate
2. Certain viral infections:papillomavirus- warts
1. Enlarged size of the uterus in pregnancy
2. Breast – puberty pregnancy, lactation
Compensatory hyperplasia
Regeneration of liver, kidney and skin
Marrow hyperplasia
METAPLASIA
• It is a reversible change in which one differentiated cell type (epithelial or mesenchymal) is replaced by another cell type
Mechanism
• Due to REPROGRAMMING of the precursor cells, present in the normal tissues.
METAPLASIA
EPITHELIAL METAPLASIA
MESENCHYMAL METAPLASIA
1. OSSEOUS METAPLASIA
1. Arterial wall
2. Myositis ossificans
3. Stroma of tumor
4. Cartilage of larynx in elderly
2. CARTILAGENOUS METAPLASIA
1. Healing of fractures
1. SQUAMOUS METAPLASIA
1. Bronchus
2. Uterine cervix
3. Gall bladder
4. Renal pelvis
2. COLUMNAR METAPLASIA
1. Barrett’s esophagus
2. Healed gastric ulcer
Post test
1. In smokers ,the ciliated columnar epithelium of trachea and bronchi are replaced by squamous epithelium. This is an example of
A. Hyperplasia B. Dysplasia C. Metaplasia D. Hypertrophy
C
• 2. Skin ‘warts’ is an example for A. Hyperplasia B. Dysplasia C. Metaplasia D. Hypertrophy
A