Module 1.2 Alterations of Cells and Tissues

Adaptation

a reversible response involving structural or functional modifications to accommodate both physiologic(normal) demands and pathologic(adverse) conditions.

Atrophy

decrease in cell size which can result in shrinking of the affected organ

Hypertrophy

increase in cell size in response to mechanical overload or stress and results in increased size of affected organ

Hyperplasia

increase in cell number due to increase in rate of cellular division, response to injury

Metaplasia

reversible replacement of one mature cell type by another less mature cell type or a change in cell phenotype

Dysplasia

deranged cellular growth; abnormal changes in the size, shape, and organization of mature cells

not considered a true cellular adaptation but rather an atypical hyperplasia

Physiologic atrophy

occurs with early development, the atrophy is a normal event

Pathologic atrophy

occurs in organs due to decrease in workload, pressure, use, blood supply, nutrition, hormonal stimulation, or neural stimulation

Autophagic vacuoles

self-destructive membrane bound vesicles that contain cellular debris and hydrolytic enzymes that degrade substances into simple units of fat, carbs, or protein

Lipofuscin

yellow-brown granules composed of lipid-containing residue that persists after lysosomal destruction

they accumulate in the liver, myocardial, renal, retinal, adrenal, and neural tissues as people age

when accumulated in the skin, they cause age spots in older adults

Physiologic hypertrophy

results from increased demand, stimulation by hormones, and growth factors

Pathologic hypertrophy

results from chronic hemodynamic overload, such as from hypertension or heart valve dysfunction

Compensatory hyperplasia(physiologic)

an adaptive mechanism that enables organs to regenerate

Hormonal hyperplasia(physiologic)

occurs in organs that respond to endocrine hormonal stimulation, maintains normal structure and function of target organs

Pathologic Hormonal hyperplasia

abnormal proliferation of normal cells, usually in response to excessive hormonal stimulation or to the action of growth factors on target cells