Hi Jack,

I would suggest you to read the attached article.

Crit Care Med. 2003 Aug;31(8 Suppl):S496-501. Mechanical injury and repair of cells. Miyake K, McNeil PL.

Best-

Cell injury is the process through which a cell is damaged and start to behave in a different manner, in some cases with negative influence to the rest of the cells and organs. The repair mechanism of a cell that was damaged is the mechanism that the cell has to restore its normal function.

Causes of cell injury:

•Oxygen deprivation

•Chemical agents

•Infectious agents

•Immunological reactions

•Genetic defects

•Nutritional imbalances

•Physical agents

•Aging

Mechanisms of Cell Injury . Adaptation- reversible injury

•Atrophy

- Shrinkage in the size of the cell (or organ) by the loss of cell substance

- Same number of cells

- E.g. pernicious anemia is associated with gastric atrophy

- Dementia is associated with brain atrophy

•Hypertrophy

- Increase in size of cells and consequently an increase in the size of the organ

- Can be physiological e.g. athletes, or pathological e.g. hypertension

- Caused by increased functional demand or hormone stimulation

•Hyperplasia

- An increase in the number of cells in an organ

- Can be physiological or pathological

- Physiological hyperplasia can be either hormonal or compensatory

- Pathological hyperplasia is usually due to excessive hormonal or growth factor stimulation

- E.g. proliferative endometrium, carcinoma

•Metaplasia

- A reversible change in which one adult cell type is replaced by another

- E.g. physiological- change in cervix during puberty

- Pathological- acid reflux through oesophagus (Barrett’s columnar lined oesophagus)

•Dysplasia

- One meaning: abnormal in form e.g. retinal dysplasia (not what we are talking about)

- Precancerous cells which show the genetic and cytological features or malignancy but not invading the underlying tissue