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

HYPERPLASIAIncrease 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)

Germinal centers are activated & Tingible

body macrophages

Follicular hyperplasia

(lymph node)

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)

HYPERTROPHYIncrease 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)

PathologicDecreased 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)

METAPLASIANonneoplastic 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

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