Cell Injury-I cellular Adaptation

Dr.Ekbal iskandar CELLULAR ADAPTATION: The ability of cells to respond to various types of stimuli and stress to escape injury CELLULAR ADAPTATION:

The cell changes that occur are: ▪ Atrophy..reduction in size and cell number ▪Hypertrophy.. enlargement of individual cells ▪Hyperplasia..increase in cell number ▪Metaplasia..transformation from one type of epithelium to another) ▪Dysplasia..disordered growth of cells

Cellular Changes

 Then anaplasia/neoplasia HYPERPLASIA Increase in the number of cells.

Physiologic hyperplasia.. normal stressor. Increase in the size of the breasts during pregnancy, Increase in thickness of endometrium during menstrual cycle, liver growth after partial resection.

Pathologic hyperplasia: proliferation of endometrium due to prolonged estrogen stimulus.

Only cells that can divide will undergo hyperplasia; hyperplasia of the myocytes in the heart and neurons in the brain does not occur. 1- FOLLICULAR HYPERPLASIA (LYMPH NODE)

2- SINUS HYPERPLASIA (LYMPH NODE) The lymph node The lymph node Follicular hyperplasia (lymph node)

▪ Nodal architecture is preserved ▪ Follicles are increased in number ▪ Variable in size and shape ▪ Margins of the follicles are sharply defined ▪ Germinal centers are activated & Tingible body macrophages (with nuclear debris) Follicular hyperplasia (lymph node) Follicular hyperplasia (lymph node)

Germinal centers are activated & Tingible body macrophages Sinus hyperplasia (lymph node)

▪ Medulla: Sinus are dilated and prominent,, often containing increased macrophages, lymphocytes and plasma cells. ▪ Cortex: atrophic or hyperplastic follicles Sinus hyperplasia (lymph node) Sinus hyperplasia (lymph node) HYPERTROPHY Increase in the size of the cell.

Physiologic hypertrophy: normal stressor. Enlargement of skeletal muscle with exercise. Hypertrophy of uterine smooth muscle during pregnancy

Pathologic hypertrophy: chronic abnormal stressor. Left ventricular hypertrophy due to long-standing increased afterload such as HTN, stenotic valves Hypertrophy of uterine smooth muscle during pregnancy ATROPHY

▪ The shrinkage in cell size by /loss of cellular substance/ ▪ Atrophied cells are smaller than normal but they are still viable (not necessarily undergo apoptosis or necrosis)

Physiologic Tissues present in embryo or in childhood (e.g., thymus) Pathologic Decreased workload Loss of innervation Decreased blood supply Inadequate nutrition Decreased hormonal stimulation Aging Fatty changes/fatty degeneration/ (lymph node)

▪ Benign mature adipocytes populate node ▪ Capsule is thinly attenuated with fine vascular trabeculae dividing fat deposits

Fatty changes/ (lymph node) METAPLASIA Nonneoplastic transformation (protective mechanism) in which one mature/adult cell type (epithelial or mesenchymal) is replaced by another mature cell type

Physiological Metaplasia: Cervical ectopy

Pathological Metaplasia. response to chronic chemical or physical stimuli: Intestinal metaplasia (Barrett metaplasia) Squamous metaplasia of the bronchi due to smoking → ciliated pseudostratified columnar epithelium to squamous epithelium Endocervical squamous metaplasia

▪ The presence of islands of squamous cells above the SCJ. ▪ It is a common physiological condition.. (Mostly due to hormonal changes that occur during puberty). ▪ Transformation of columnar endocervical epithelium to squamous ectocervical-like epithelium. Squamous metaplasia Squamous metaplasia. Uterine cervix Squamous metaplasia. Respiratory mucosa Barrett's esophagus, intestinal metaplasia Barrett’s Esophagus Intestinal Metaplasia of the Esophagus

THANK YOU