Disorders of tissue growth Flashcards
Describe the 3 cells are involved in normal tissue growth?
Labile cells - continuously dividing, proliferate throughout life, replacing those that are lost
Stable cells - cells with low levels of replication, but in response to stimuli undergo rapid division
Permanent cells - non-dividing, have left the cell cycle and cannot undergo mitotic division
Give some examples of labile cells
Epithelia, epidermis, intestinal mucosa
Adult stem cells
Give some examples of stable cells
Mesenchymal cells (fibroblasts, osteocytes, liver, kidney, pancreas
Give some examples of permanent cells
Neurones
Heart muscle cells
What are stem cells?
Cells that lack fully differentiated morphological, functional and behavioural characteristics
Which cells have the ability to give rise to all tissues of the body?
Totipotent embryonic stem cells
Which cells can give rise to a smaller variety of tissue types?
Pluripotent, adult stem cells
Compare agenesis and aplasia
Agenesis = absence of an organ or body part (no first tract of this structure) Aplasia = failure of an organ to develop (usually accompanied by the presence of a rudimentary organ)
The terms metaplasia, dysplasia and anaplasia all come under which category?
Abnormal cell growth
What is hypoplasia?
Failure of an organ to develop to its full size - growth stops
Causes - unknows, genetic, hormone, infectious agent
What is atrophy?
Shrinkage of an organ or tissue after it has reached its normal size, caused by a reduction of cell size or number
Compare qualitative and quantitative atrophy
Qualitative - cells shrink = reduction in size
Quantitative - cell death exceeds replacement = reduction in number
What are some possible causes for cell atrophy?
- Lack of nutrients
- Lack of blood supply
- Lack of innervation
- Disease
- Loss of hormonal stimulation
What are the 3 methods of increased growth?
Hyperplasia
Hypertrophy
Neoplasia
Define hyperplasia
An increase in the size of an organ due to an increase in cell number - increases mitotic division
It is a reversible change
What triggers hyperplasia and hypertrophy?
Hormones
Growth factors
Cytokines
Transcription factors
Give 2 examples of hyperplasia in the body
- Mammary gland hyperplasia in response to increased hormonal stimulation during pregnancy and lactation
- Compensatory liver hyperplasia after a hepatectomy
Define hypertrophy
An increase in the size of an organ due to an increase in cell size - more organelles
It is a reversible change
What is the only type of morphological change in growth that can happen in permanent cells?
Hypertrophy
What is the overall cause of hypertrophy?
Demands for increased function
Define metaplasia
A reversible change in which one adult cell type is replaced by another adult cell type
- A highly specialised tissue is replaced by a less specialised but more resistant tissue
- Used for protection
If the metaplastic injurious stimulus persists what can it lead to?
Neoplastic transformation
How can chronic irritation affect the epithelium?
Transformation from columnar to squamous
Define dysplasia
Loss of uniformity of the individual cells as well as loss in their architectural orientation
- Epithelium undergo disordered growth and maturation
How is dysplasia characterised grossly and microscopically?
- Loss of uniformity of the individual cells and disorganisation, variation in the size and shape of cells and their nuclei
What is the most common cause of dysplasia?
Chronic inflammation
