How to Distinguish Between Hyperplasia, Hypertrophy, Necrosis, Atrophy & Apoptosis
Topic 1 - Cellular Changes in Disease
What is Hyperplasia?
An INCREASE in the NUMBER of cells due to an adaptive change e.g. the removal of a kidney
What is Hypertrophy?
An INCREASE in the SIZE of cells due to an adaptive change e.g. half a heart not functioning
What is Atrophy?
A DECREASE in the SIZE of cells, failure to adapt to change, loos of cytoskeleton and organelles e.g. muscular dystrophy
What is Metaplasia?
One adult cell is replaced with a different adult cell
What is Dysplasia?
An abnormal change in size, shape and organisation (not adaptive)
What is Necrosis?
Necrosis is cell death caused by injured cells, usually by enzymes or denatured proteins.
Types of necrosis include Coagulative, Liquefaction or Casseous
- Coagulative necrosis - Occurs in the heart, kidney and adrenal glands. Results from ischemia or hypoxia caused by chemical injury and protein degradation. The albumin changes appearance, there is an increase in intracellular Ca 2+. The Cell outline is preserved so there is no autolysis. An example of coagulative necrosis is myocardial infarction.
- Liquefaction necrosis - Results from ischemic injury or stroke to neurons and glial cells within the brain and spiral cord (Central Nervous System). Brain cells are affected due to an increase in hydrolytic enzymes, lipids and low connective tissues. Hydrolases digest cells causing tissues to become soft and start to liquify.
- Casseous necrosis - Results from bacterial infection, for example, Tuberculosis (Mycobacterium tuberculosis), cells from granuloma, the cell center dies and develops a white cheese-like appearance under the microscope.
What is Apoptosis?
Occurs when cell damage is beyond repair. Apoptosis is a programmed isolated cell death which is triggered by the p53 gene. The nucleus is denatured, organelles become larger, cell fragments shrink and are removed by phagocytes. Some types of apoptosis cause mutation in the p53 gene which lead to failed apoptosis, replication of genetically altered cells and cancer developing in some cases.
What are cell inclusions?
Cellular disease increases the amounts of deposits and vacuoles within the cells. Deposits including calcium, fats, protein, glycogen, toxic metabolites and inert substances which interfere with cell function.Click here to head back to the Main Menu
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