#metaplastic

[cancerrific]

Is it weird that part of me really wishes I had been able to see my tumor after they took it out? Just to be able to look at it accusingly and say "There you are, you bastard"

[pathologyfornurses-blog]

2. cellular pathology

cells adapt to changes in their environment and in their work demands by changing their size, number, and characteristics.

These adaptive changes are consistent with the needs of the cell and occur in response to an appropriate stimulus. The changes are usually reversed after the stimulus has been withdrawn.

Hypo-trophy= When confronted with a decrease in work demands or ad- verse environmental conditions, cells atrophy or reduce their  size and revert to a lower and more efficient level of functioning.

Hypertrophy results from an increase in work demands and is characterized by an increase in tissue size brought about by an increase in cell size and functional components in the cell.

hyperplasia= An increase in the number of cells in an organ or tissue that is still capable of mitotic division.

Metaplasia occurs in response to chronic irritation and represents the substitution of cells of a type that are better able to survive under circumstances in which a more fragile cell type might succumb.

Dysplasia is characterized by deranged cell growth of a specific tissue that results in cells that vary in size, shape, and appearance. It is a precursor of cancer.

Under some circumstances, cells may accumulate abnormal amounts of various substances. If the accumulation reflects a correctable systemic disorder, such as the hyperbilirubinemia that causes jaundice, the accumulation is reversible. If the disorder cannot be corrected, as often occurs in many inborn errors of metabolism, the cells become overloaded, causing cell injury and death.

Pathologic calcification involves the abnormal tissue deposition of calcium salts. Dystrophic calcification occurs in dead or dying tissue. Although the presence of dystrophic calcification may only indicate the presence of previous cell injury, it is also a frequent cause of organ dysfunction (e.g., when it affects the heart valves).

Metastatic calcification occurs in normal tissues as the result of elevated serum calcium levels. Almost any condition that increases the serum calcium level can lead to calcification in inappropriate sites such as the lung, renal tubules, and blood vessels

cell injury can be caused by a number of agents, including physical agents, chemicals, biologic agents, and nutritional factors. Among the physical agents that generate cell injury are mechanical forces that produce tissue trauma, extremes of temperature, electricity, radiation, and nutritional disorders.

Chemical agents can cause cell i1njury through several mechanisms: they can block enzymatic pathways, cause coagulation of tissues, or disrupt the osmotic or ionic balance of the cell. Biologic agents differ from other injurious agents in that they are able to replicate and continue to produce injury. Among the nutritional factors that contribute to cell injury are excesses and deficiencies of nutrients, vitamins, and minerals.

Injurious agents exert their effects largely through generation of free radicals, production of cell hypoxia, or unregulated intracellular calcium levels.

Partially reduced oxygen species called free radicals are important mediators of cell injury in many pathologic conditions. They are an important cause of cell injury in hypoxia and after exposure to radiation and certain chemical agents.

Lack of oxygen underlies the pathogenesis of cell injury in hypoxia and ischemia. Hypoxia can result from inadequate oxygen in the air, cardiorespiratory disease, anemia, or the inability of the cells to use oxygen. Increased intracellular calcium activates a number of enzymes with potentially damaging effects.

Injurious agents may produce sublethal and reversible cellular damage or may lead to irreversible cell injury and death. Cell death can involve two mechanisms: apoptosis and necrosis. Apoptosis involves controlled cell destruction and is the means by which the body removes and replaces cells that have been produced in excess, developed improperly, have genetic damage, or are worn out. Necrosis refers to cell death that is characterized by cell swelling, rupture of the cell membrane, and inflammation.