Cellular Adaptation Flashcards
Purpose of cellular adaptation
The ability of cells to adapt to changes in their environment is the difference between a cell living or not
Inability to adapt leads to cell injury and death
Hyperplasia
An increase in cell number results in an increased volume of the organ/tissue
Can be physiological or pathological
Local production of growth factors increases receptor expression on target cells
This causes activation of intracellular growth pathways
Hypertrophy
An increase in cell size results in an increase in the size of the organ
Can be pathological or physiological
Caused by increased functional demand or hormone stimulation
- Insulin-like growth factor = physiological hypertrophy
- Angiotensin II - pathological hypertrophy
Cardiac hypertrophy
Cardiac hypertrophy is always pathological
An increased workload causes the cardiac cells to increase in size, leading to a decrease in the size of heart chambers
Atrophy
A decrease in cell size AND number results in a decrease in the size of the organ
Can be physiological or pathological
Caused by decreased workload, loss of innervation, pressure etc.
Tissue healing
The healing response involves a combination of regeneration and scar formation (fibrosis) by deposition of collagen
The exact proportion of each response depends on the severity of the injury and the ability of the tissue to regenerate
Terminally differentiated cells
Differentiated cells incapable of replication
Damage to this cells will result in their replacement with fibroblasts
Examples include cardiac myocytes
Pluripotent stem cells
Cells that can differentiate into all types of cells
Found in embryos
Arise from an inner cell mass called a blastocyst
Multipotent/unipotent stem cells
Cells that can differentiate into different cells types, but are more restricted
Induced pluripotent stem cells
Differentiated adult cells that have been reprogrammed in the lab to become pluripotent
Created by transferring the nucleus of a differentiated cell to an enucleated oocyte
Applications of stem cell technology
- To study development of tissues
- To produce knockout mice
- To regenerate damaged organs
Disadvantages of stem cell technology
The cells may become cancerous if their proliferation is not properly controlled
