17. Abnormalities of growth, differentiation and morphogenesis Flashcards
What is a cellular adaptation?
Reversible changes in cellular size/number/phenotype/metabolic activity/function due to changes in 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
What is the role of cellular adaptation?
- 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. Give examples
Cerebral neurons = very sensitive to hypoxia, rapidly die when subject to hypoxic stress
Fibroblasts = very resistant to damage, can survive for long periods in challenging environments
Depending on the cell population type, tissues either
- don’t need to adapt
- adapt easily
- cannot adapt
Give an example of a tissue type that does not need to adapt
Fibroblasts
Survive severe metabolic stress without harm eg. absence of O2
Depending on the cell population type, tissues either
- don’t need to adapt
- adapt easily
- cannot adapt
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
Depending on the cell population type, tissues either
- don’t need to adapt
- adapt easily
- cannot adapt
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
What is PATHOLOGICAL cellular adaptation?
Responding to disease related changes
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
Increase in SIZE of cells is called what?
Hypertrophy
Increase in NUMER of cells is called what?
Hyperplasia
Hypertrophy and hyperplasia may co-exist. What do they both lead to?
Hypertrophy/hyperplasia = increased cell mass = increased capacity
Hypertrophy is an increase in size of existing cells and therefore an increase in functional capacity. What does this 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
Under what circumstances might a uterus be pathologically hypertrophied?
Adhered placenta causing post-partum haemorrhage
Causes uterus to be significantly larger after delivery
The prostate becomes enlarged as part of the ageing process, by a process of ….? hyperplasia
Adenomyomatous hyperplasia
When the prostate undergoes hyperplasia, what effect does this have on the bladder?
Detrusor muscle has to work harder during micturition - undergoes hyperplasia
Hyperplasia of the prostate can lead to further hyperplasia of the detrusor muscle of the bladder. What appearance does this give?
Trabeculated appearance
Can also get bladder diverticuli
Permanent cell populations can only respond to increased demand by doing what?
Increasing cell size
hypertrophy
