5.6 Tissue Modification, Aging, and Tissue Transplant (Vocabulary)

Vocabulary flashcards covering key terms from 5.6 Tissue Modification, Aging, and Tissue Transplant, including hypertrophy/hyperplasia, atrophy/metaplasia/dysplasia, neoplasia, necrosis/gangrene, stem cell potency, embryonic vs adult stem cells, and autograft/isograft/allograft/xenograft concepts, plus aging of tissues.

Hypertrophy

Increase in the size of existing cells in a tissue; the number of cells remains constant.

Hyperplasia

Increase in the number of cells in a tissue.

Atrophy

Shrinkage of tissue due to a decrease in cell size or cell number (aging or disuse can cause it).

Metaplasia

Transformation of a mature epithelium into a different form of mature epithelium, often as an environmental adaptation (e.g., smokers’ tracheal epithelium).

Dysplasia

Abnormal tissue development; often precancerous and may progress to cancer or revert to normal tissue.

Neoplasia

Abnormal tissue growth that forms a tumor; neoplasms may be benign or malignant.

Benign neoplasm

Localized growth that does not spread to other tissues.

Malignant neoplasm

Invasive growth that can spread (metastasize) to other tissues; cancer.

Cancer

Common term for a malignant neoplasm; often involves DNA damage and potential systemic effects.

Necrosis

Tissue death due to irreparable damage, usually with an inflammatory response.

Gangrene

Necrosis of tissue due to diminished or obstructed blood supply; includes dry, wet, and gas forms.

Dry gangrene

Desiccated, sharply demarcated, shriveled tissue usually from constricted blood vessels or cold exposure.

Wet gangrene

Gangrene associated with bacterial infection, loss of blood/oxygen, pus, and foul odor.

Gas gangrene

Gangrene in which Clostridium bacteria produce gas in necrotic tissue, causing crackling under movement.

Stem cells

Immature, undifferentiated cells capable of self-renewal and differentiation into multiple cell types.

Self-renewal

Ability of stem cells to divide and produce more stem cells (maintains the stem cell pool).

Potency

Potential of stem cells to differentiate into various cell types; levels include totipotent, pluripotent, multipotent, and unipotent.

Totipotent

Total potential; can form any cell type and placenta; derived from the zygote; embryonic cells are totipotent.

Pluripotent

Can form cells from all embryonic germ layers but cannot form placenta; derived from embryoblast; includes iPSCs.

Induced pluripotent stem cells (iPSCs)

Adult cells reprogrammed to behave like pluripotent embryonic stem cells.

Multipotent

Can differentiate into a restricted set of cell types (e.g., hematopoietic stem cells).

Unipotent

Can differentiate into a single cell type but can renew themselves (e.g., epithelial stem cells).

Embryonic stem cells

Pluripotent stem cells derived from the zygote or blastocyst with broad differentiation potential.

Adult stem cells

Stem cells in postnatal organisms; usually multipotent or unipotent and less potent than embryonic stem cells.

Autograft

Tissue graft from one site to another in the same individual; no rejection since it’s the same person.

Syngeneic graft (isograft)

Graft between genetically identical individuals (e.g., identical twins); practically rare.

Allograft

Tissue transplant from one person to another genetically different individual; risk of rejection; requires immunosuppression.

Xenograft (heterograft)

Tissue transplant from an animal to a human; high rejection risk; examples include pig or cow tissues.

Grafting

Process of surgically transplanting healthy tissue to replace diseased or damaged tissue.

Aging of tissues

Age-related changes: epithelia thin, collagen declines, connective tissue loses pliability, repair slows, bones stiffen, muscles/nerves atrophy, and lifestyle factors (poor diet, circulation problems, alcohol, smoking) accelerate decline.