L17 - Abnormalities of growth, differentiation and morphogenesis Flashcards
What is a cellular adaptation?
Reversible changes in cells due to environment or demand
During cellular adaptation, the cell may make changes in what?
- size
- number
- phenotype
- metabolic activity
- function
How is cellular adaptation different to cell injury and neoplasia?
Cell injury and neoplasia are irreversible whereas cellular adaptation is most often reversible
Why do cells adapt?
- acquire new, steady state of metabolism and structure
- better equips cell to survive in new environment
What may failure of adaptation lead to?
Sub-lethal or lethal cell injury
- marked susceptibility to injury
- stimulus is too severe
Tissues differ in their susceptibility to stress.
How do cerebral neurones compare to fibroblasts?
Cerebral neurones = very sensitive to hypoxia (stress), rapidly die when subject to hypoxic stress
Fibroblasts = very resistant to damage (especially oxygen), can survive for long periods in challenging environments
Give an example of a tissue type that does not need to adapt
Fibroblasts
Survive severe metabolic stress without harm eg. absence of O2
Give an example of a tissue type that can adapt easily
Epithelial cells
Labile cell population, active stem cell population, highly adaptive in number and function
Give an example of a tissue type that cannot adapt
Cerebral neurons
Terminally differentiated, permanent cell population, highly specialised function, easily damaged by environmental change
What is PHYSIOLOGICAL cellular adaptation?
Responding to normal changes in physiology or demand
e.g muscles grow during work outs
What is PATHOLOGICAL cellular adaptation?
Responding to disease related changes
e.g Broken arm and immobility causing muscles to die off
What are 3 types of adaptive responses?
- increased cellular activity
- decreased cellular activity
- changes in cell function and/or morphology
In what ways can a cell adapt to increase cellular activity?
Increase size and/or number of cells
In what ways can a cell adapt to decrease cellular activity?
Decreased size and/or number of cells
What is hypertrophy?
increase in size of cells
what is hyperplasia?
increase in number of cells → increased cell mass
Hypertrophy and hyperplasia may co-exist. What do they both lead to?
Hypertrophy/hyperplasia = increased cell mass = increased capacity
What 2 things does hypertrophy lead to?
- increased synthesis of structural components
- increased metabolism
In which tissues is hypertrophy particularly seen in?
Permanent cell populations, especially cardiac and skeletal muscle
NB: they tend to get bigger in terms of size rather than number
Under what circumstances might a uterus be pathologically hypertrophied?
post-partum haemorrhage
Causes uterus to be significantly larger after delivery
Permanent cell populations can only respond to increased demand by doing what?
Increasing cell size
hypertrophy
What causes left ventricular hypertrophy?
- atheroma plaque
- calcification of valve cusps leading to inflexibility and narrowing of orifice (hard to push blood through)
How might you diagnose left ventricular hypertrophy?
- clinical examination
- ECG
- imaging
Which valve abnormality would lead to left ventricular hypertrophy (LVH)?
Aortic stenosis