Cellular adaptation

Question 1

What cellular adaptations are possible and what are they due to?

Answer 1

Size
Number
Phenotype
Metabolic activity
Function
due to changes in the environment or demand

Question 2

What is the role of cellular adaptation?

Answer 2

• Acquire new, steady state of metabolism and structure
• Better equips cells to survive
• Failure of adaptation may lead to (sub)-lethal cell injury

Question 3

Give examples of cells which cannot, can easily and don’t need to adapt.

Answer 3

CANNOT= Cerebral neurons, terminally differentiated, permanent cells
DON'T= Fibroblasts, survive severe metabolic stress without harm
EASILY= epithelial, labile, active stem cells

Question 4

What are physiological and pathological cellular adaptations?

Answer 4

Physiological= Responding to normal changes in physiology or demand
Pathological = Responding to disease related changes

Question 5

What are types of adaptive responses?

Answer 5

• Inc cellular activity= inc size/no. of cells
• Dec cellular activity= Dec size/no. of cells
• Change of cell function and morphology

Question 6

What is the point of hypertrophy?

Answer 6

• Increase in functional capacity
• Increased synthesis of structural components
• Increased metabolism
• Particularly in permanent cell populations-cardiac/skeletal muscle

Question 7

What are problems associated with left ventricular hypertrophy?

Answer 7

• VT/VF/sudden cardiac death

- Ectopic beats leading to abnormal rhythm

Question 8

Give an example of sub cellular hypertrophy

Answer 8

• Inc in size of certain organelles

- Smooth ER hypertrophy in hepatocytes in barbiturate use= inc metabolism of other drugs

Question 9

What is Graves disease?

Answer 9

• 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

Question 10

Give examples of pathological and physiological atrophy

Answer 10

Pathological= localised/generalised
Physiological= embryogenesis, uterus after pregnancy/menopause

Question 11

What does pathological atrophy lead to?

Answer 11

• Dec workload (disuse atrophy)
• Loss of innervation (denervation atrophy)
• Diminished blood supply
• Inadequate nutrition (cachexia)
• Pressure
• Loss of endocrine stimulation

Question 12

What are developmental causes of reduced cell mass?

Answer 12

• 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

Question 13

What is metaplasia?

Answer 13

• 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

Question 14

Give some examples of pathological causes of metaplasia

Answer 14

• 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

Question 15

Name the adaptations and the potential cancer that can be caused

Answer 15

-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

Question 16

Describe the term dysplasia

Answer 16

• In-situ
• Earliest morphological manifestation of multistage process of neoplasia
• Shows cytological features of malignancy but no invasion