Cell Adaptation

30 .Sept. 2013

Adaptations

• Adaptations; are functional and structural responses to more severe physiologic or pathologic stimuli,

give new, altered steady states,

allow cells to survive & function• The adaptive response may consist of

(hypertrophy), (hyperplasia), (atrophy), or (metaplasia).

• Reversible changes.

Stages of cellular response to stress & injurious stimuli.

Skeletal muscle hypertrophy

Hypertrophy; the muscle cells synthesize more proteins and the number of myofilaments increases

Cardiac hypertrop

hy involv left vent.

HYPER-TROPHY

IN-CREASE IN SIZE OF CELLS

Physiologic hypertrophy of the uterus during pregnancy. A, Gross appearance of a normal uterus (right) and a gravid uterus (left). B, Small spindle-shaped uterine smooth muscle cells from a normal uterus (left) compared with large plump cells in gravid uterus (right).

HYPER-PLASIAIN-CREASE IN NUMBER OF CELLS

a. Adult breast tissue. B. lactating breast

Physiologic Hyperplasia; hormonal hyperplasia

Bone Marrow hyperplasia in anemia

Physiologic Hyperplasia; compensatory hyperplasia

Endometrial hyperplasi (physiological &

pathological) .

Pathologic Hyperplasia Nodular prostatic hyperplasia, or BPH. The normal prostate is 3 to 4 cm in

Nodular prostatic hyperplasia

a. Adult breast tissue. B. lactating breast

Physiologic Hyperplasia; hormonal hyperplasia

Hyperplasia is also an important response of connective tissue cells in wound healing

ATROPHY?DE-CREASE IN SIZE OF CELLS

SHRINKAGE IN CELL SIZE DUE TO LOSS OF CELL

SUBSTANCE

ATROPHY• DECREASED WORKLOAD• DENERVATION• DECREASED BLOOD FLOW• DECREASED NUTRITION• AGING (involution)• PRESSURE

Skeletal muscle hypertrophy

This is cerebral atrophy in a patient with Alzheimer disease. The gyri are narrowed and the intervening sulci widened, particularly pronounced toward the frontal lobe region.

Right testicular atrophy.

METAPLASIA• A SUBSTITUTION of one NORMAL CELL or

TISSUE type, for ANOTHER– COLUMNAR SQUAMOUS (Cervix)– SQUAMOUS COLUMNAR (Glandular)

(Stomach)– FIBROUS BONE

–WHY?

Metaplasia. A, Schematic diagram of columnar to squamous metaplasia. B, Metaplastic transformation of esophageal stratified squamous epithelium (left) to mature columnar epithelium (so-called Barrett metaplasia).

Metaplasia of the normal esophageal Squamous mucosa, with the appearance of gastric columnar mucosa

                                               

Metaplasia of laryngeal respiratory epithelium in a smoker..