PP 7 Cellular Adaptations Flashcards
What is the size of cell population dependent on?
Cell proliferation
Cell differentiation
Cell death by apoptosis
What causes increase in cell numbers?
Decreased cell death
Increased cell proliferation
What is normal cell proliferation regulated by?
Tumour suppressors
Proto-oncogenes
What is cell adaptation?
State between a normal unstressed cell + overstressed injured cell
List cell adaptations
Hyperplasia
Hypertrophy
Atrophy
Metaplasia
Hyperplasia meaning
Increased cell number
Hypertrophy meaning
Increased cell size
Atrophy meaning
Decreased cell size or number
Metaplasia meaning
Cells are replaced by different cell type
What are the types of physiological hyperplasia?
Hormonal
Compensatory
What is hormonal hyperplasia a result of?
Need for increased functional capacity
What is compensatory hyperplasia a result of?
Need of an increase in tissue mass after tissue damage
Causes of pathological atrophy
Decreased work load
Loss of innervation
Decreased blood supply
Inadequate nutrition
Persistent injury
Loss of endocrine stimulation
Aging
Pressure
Occlusion of secretory duct
Toxic agents
X rays
Immunological disease
Where is metaplasia most common in?
What happens?
Epithelial tissues
Columnar epithelium > squamous epithelium
(fragile) (more resistant)
Where does metaplasia not occur?
Across germ layers e.g. bone > nerve
In adult striated muscle or neurones
What can happen in metaplasia?
Loss of function
Is hyperplasia reversible?
Yes
Is metaplasia reversible?
Yes
Examples of physiological hyperplasia
Proliferation of endometrium from oestrogen
Bone marrow production of RBCs
Aplasia meaning
Complete failure of specific tissue or organ to develop
Hypoplasia meaning
Congenital underdevelopment or incomplete development of tissue or organ
Atresia meaning
Congenital absence/narrowing of an opening
Reconstitution meaning
Replacement of a lost body part
Involution meaning
Normal programmed shrinkage of organ
Dysplasia meaning
Abnormal maturation of cells within a tissue
Neoplasia meaning
New, abnormal tissue growth
Example of hypertrophy
- Smooth muscle hypertrophy of uterus in pregnancy due to oestrogen
- cardiac muscle of heart in exercise
What is the best way to treat atrophy?
Treat the cause
Types of atrophy
Atrophy of disuse
Senile atrophy
Pressure atrophy
Denervation atrophy
Cause of senile atrophy
Inadequate blood supply
Where does senile atrophy occur?
Permanent tissue
Cause of atrophy of disuse
Decreased work load
e.g. excessive bed rest after injury/surgery
Fat can convert x to y ?
Androgens (testosterone) to oestrogen
What can too much oestrogen cause?
Endometrial hyperplasia
Breast cancer
Clinical use of tamoxifen
To reduce the chance of breast cancer coming back
Blocks oestrogen receptors in breasts
Side effect of tamoxifen
Stimulates oestrogen receptors in endometrium
Can cause endometrial hyperplasia
Long term complication of endometrial hyperplasia
Endometrial cancer
Common causes of myocardial hypertrophy
Mitral valve regurgitation
Ischaemic heart disease
Exercise
Stenosis of outflow tracts
Examples of pathological hyperplasia
- epidermal thickening
Examples of physiological hypertrophy
Body builders - skeletal muscle
Pregnant uterine cells
Examples of pathological hypertrophy
Ventricular hypertrophy
Bladder smooth muscle hypertrophy
