Pathophysiology Chapter 2 (Cellular Injury, Adaptations, and Maladaptive Changes)

etiology

the original cause of a cellular alteration or disease

histology

the microscopic study of tissues and cells that yields important diagnostic information for the clinician

biopsy

extracts a cell sample from an organ or mass of tissue to allow for histological examination

pathognomonic changes

unique histological findings that represent distinct disease processes

atrophy

a cellular adaptation in which cells revert to a smaller size in response to changes in metabolic requirements or their environment; occurs when a cell's environment cannot support its metabolic requirements

hypertrophy

an increase in individual cell size that results in an enlargement of functioning tissue mass; each individual cell becomes larger; increases the cell's functional components, which leads to greater metabolic demand and energy needs

angiogenesis

the growth of new blood vessel branches

physiologic hypertrophy

the enlarged muscle is adequately perfused and supplied with blood flow, oxygen, and nutrients because of angiogenesis

pathological hypertrophy

occurs when there is an increase in cellular size without an increase in the supportive structures necessary for the enlarged cell's increased metabolic needs; can occur in disease processes or may be a compensatory maladaptation to changed environmental conditions

ischemia

inadequate blood flow

hyperplasia

the increase in the number of cells in a tissue or organ; only occurs in tissues with cells that are capable of mitotic division, such as the epithelium and glandular tissue; stimulated by hormonal or compensatory cellular mechanisms (benign prostatic hyperplasia - BPH) - can also occur as a maladaptive compensatory mechanism when it overcompensates by exceeding the cell mass necessary for regeneration (keloid)

metaplasia

the replacement of one cell type by another cell type; likely a result of the cell's genetic reprogramming in response to a change in environmental conditions

dysplasia

deranged cellular growth within a specific tissue, often as a result of chronic inflammation or a precancerous condition; on histological examination, dysplastic cells vary in size, shape, and architectural organization compared with healthy cells

neoplasia

means new growth and usually refers to disorganized, uncoordinated, uncontrolled proliferative cell growth that is cancerous

well-differentiated neoplasms

neoplastic cells that resemble the normal, healthy cells within the tissue where they are found; benign

poorly-differentiated neoplasms

appear very different from the healthy cells within their tissue of origin; malignant

basic concepts of cellular injury

*dysfunction of the sodium-potassium pump (calcifications)

*loss of plasma membrane integrity (cellular swelling)

*defects in protein synthesis ability (cell degeneration or cell death)

*intracellular accumulations (bilirubin; xanthomas)

*genetic damage (mutations --> changes in cell structure and function --> incompatible with life --> apoptosis)

causes of cell injury

*hypoxic cell injury

*free radical injury

*physical agents of injury (sunburn, excessive noise)

*chemical injury (endogenous biological substances, exogenous, synthetic substances)

*infectious agents of injury (HPV, H. pylori)

*injurious immunological reactions (allergies, autoimmune diseases)

*genetic defects

*nutritional imbalances (obesity)

oxidative stress

a form of cell injury caused by free radical generation that overwhelms the cell's mechanisms of removal

aneurysm

a weakened area in an arterial wall

atherogenesis

the gradual and progressive development of atherosclerotic plaque within the arteries that is initiated by endothelial injury

apoptosis

a genetically programmed degenerative change that results in cell death

infarction

also called ischemic necrosis; the death of tissue as a consequence of prolonged ischemia

gangrene

occurs when tissues endure prolonged ischemia, undergo infarction and necrosis, and then are exposed to bacteria that thrive on the decaying tissue