Abnormalities of growth, differentiation and morphogenesis Flashcards
Give an example of cells that cannot adapt and why.
Cerebral neurons
- Terminally differentiated
- Permanent cell population
- Highly specialised function
- Easily damaged by environmental change
Give an example of cells that are good at adapting.
Epithelial cells
- Labile cell population
- Active stem cell compartment
- Highly adaptive in number and function
Give an example of cells that don’t need to adapt.
Fibroblasts
- Survive severe metabolic stress without harm
- eg absence of O2
What is hypertrophy?
Increase in the size of cells.
Increase in functional capacity.
Particularly seen in cardiac cells.
What is subcellular hypertrophy/hyperplasia?
Increase in size/number of cellular organelles.
Eg ER hypertrophy in barbiturate use -> increased metabolism of other drugs
What is hyperplasia?
Increase in number of cells caused by cell division
Possible in labile and stable cell populations
What are the possible physiological mechanisms behind hyperplasia?
Hormonal
Compensatory
What are the possible pathological mechanisms behind hyperplasia?
Excess hormones
Growth factors
What is gynecomastia?
Enlargement of the male breast due to hyperplasia of the glandular and stromal tissue in the breast. This can be physiological at puberty, related to drugs – either prescribed or recreational (anabolic steriods, oestrogen) or to pathology elsewhere such as cirrhosis of the liver.
What is atropy?
Reduction in size of organ or tissue by decrease in cell size and number
Physiological - embryogenesis, uterus after pregnancy or menopause
Pathological - localised or generalised
What are the features of pathological atrophy?
- Decreased workload (disuse atrophy)
- Loss of innervation (denervation atrophy)
- Diminished blood supply
- Inadequate nutrition (eg cachexia)
- Loss of endocrine stimulation
- Pressure
What are the possible mechanisms of atrophy?
- Reduction in volume of individual cells
- Death of individual cells
What is involution?
Physiological atrophy due to apoptosis.
What is metaplasia?
Transformation of one differentiated cell type into another
Transdifferentiation of stem cells
Better adaptation to new environment
Can affect epithelium and mesenchymal tissues
Physiological or pathological
Give examples of metaplastic tissues.
Pseudostratified ciliated bronchial epithlium -> sqaumous
Transitional epithelium of bladder -> sqamous
Fibrocollagenous tissue -> bone
Oesophageal sqaumous epithelium -> columnar (glandular) epithelium
