Cellular adaptation Flashcards
What cellular adaptations are possible and what are they due to?
Size Number Phenotype Metabolic activity Function due to changes in the environment or demand
What is the role of cellular adaptation?
- Acquire new, steady state of metabolism and structure
- Better equips cells to survive
- Failure of adaptation may lead to (sub)-lethal cell injury
Give examples of cells which cannot, can easily and don’t need to adapt.
CANNOT= Cerebral neurons, terminally differentiated, permanent cells DON'T= Fibroblasts, survive severe metabolic stress without harm EASILY= epithelial, labile, active stem cells
What are physiological and pathological cellular adaptations?
Physiological= Responding to normal changes in physiology or demand Pathological = Responding to disease related changes
What are types of adaptive responses?
- Inc cellular activity= inc size/no. of cells
- Dec cellular activity= Dec size/no. of cells
- Change of cell function and morphology
What is the point of hypertrophy?
- Increase in functional capacity
- Increased synthesis of structural components
- Increased metabolism
- Particularly in permanent cell populations-cardiac/skeletal muscle
What are problems associated with left ventricular hypertrophy?
- VT/VF/sudden cardiac death
- Ectopic beats leading to abnormal rhythm
Give an example of sub cellular hypertrophy
- Inc in size of certain organelles
- Smooth ER hypertrophy in hepatocytes in barbiturate use= inc metabolism of other drugs
What is Graves disease?
- Autoantibody binds to and switches on TSH recpetor
- Leads to prolonged, uncontrolled hyperplasia of thyroid and hyperthyroidism
- Eye signs= exophthalmos by abnormal deposits of ground substance in orbital tissues
Give examples of pathological and physiological atrophy
Pathological= localised/generalised Physiological= embryogenesis, uterus after pregnancy/menopause
What does pathological atrophy lead to?
- Dec workload (disuse atrophy)
- Loss of innervation (denervation atrophy)
- Diminished blood supply
- Inadequate nutrition (cachexia)
- Pressure
- Loss of endocrine stimulation
What are developmental causes of reduced cell mass?
- AGENESIS= failure of embryonic cell mass to differentiate to organ-specific tissue
- APLASIA= failure of organ tissue to become an organ by structural organisation
- DYSGENESIS= failure of organ to grow to full size
- HYPOPLASIA= failure of ‘normal’ organ
What is metaplasia?
- Transformation of one differentiated cell type to another
- Transdifferentiation of stem cells
- Better adaptation to environment
- Can affect epithelium/mesenchymal tissues
- Physiological (cervix) or pathological
Give some examples of pathological causes of metaplasia
- Psuedostratified ciliated bronchial epithelium= cigarette smoke= squamous epithelium
- Transitional epithelium of bladder= longstanding catheter, schistomosiasis, bladder calculus= squamous epithelium
- Fibrocollagenous tissue=chronic trauma= bone
- Oesophageal squamous epithelium, acid reflux, columnar epithelium
Name the adaptations and the potential cancer that can be caused
-Squamous metaplasia in cervix= CIN & squamous cell carcinoma
-Squamous metaplasia in bronchus= Dysplasia & squamous cell carcinoma
-Glandular metaplasia in oesophagus= Adenocarcinoma
-Parathyroid hyperplasia due to chronic renal failure= Adenoma
Endometrial hyperplasia due to inc oestrogen= Adenocarcinoma