CHAPTER FOUR: INTRACELLULAR ACCUMULATIONS
Effects of Intracellular Accumulations The presence of an intracellular accumulation may have no effect on cell function, or it may impair normal cellular operations and result in cell injury or death. Even in cases where an accumulation has no influence on cell function, we must treat the accumulation as significant. An intracellular accumulation is always of abnormal function somewhere in the body. The dysfunction associated with intracellular accumulation may be local or may be occurring in an unrelated system or tissue.
There are three general pathways for intracellular accumulation to occur:
1. The first scenario involves accumulation of an metabolite. This situation indicates that there is some dysfunction in the system that normally processes and removes that metabolite, or that there is excessive intake of a substance that has over saturated the systems that regularly process that substance. Metabolite accumulation is seen in individuals with diabetes . The mechanism for stimulating the uptake of glucose from the blood and for lipogenesis is reduced or not functioning. Over time this results in the accumulation of glycogen in cells that do not normally store glycogen if dietary sugar intake is not controlled for an extended period of time. , non-metabolizable substance is introduced into the body. For example, the injection of inorganic pigments into the cells of the skin results in the accumulation of those pigments in the epithelium, as in a tattoo . Today the pigments found in tattoo ink are tested to ensure that they have no impact on cell function, though in the past some pigments have contained toxic substances such as lead and arsenic. 2. The second situation in which intracellular accumulation occurs is when an 3. The third occasion in which intracellular accumulation occurs is when there is production of a normally occurring molecule. Over production is usually a result of a genetic mutation that disables the normal regulatory pathways for production of a particular molecule. For example, individuals with Addison’s disease exhibit an over production of the normally occurring skin pigment melanin. This results in areas of hyper pigmentation in the skin. Common Intracellular Accumulations There are a number of commonly seen intracellular accumulations, whose mechanisms are well understood. The presence of one or more of these accumulations can be indicative of disease and may be useful in the diagnosis of and the monitoring of disease. Glycogen Accumulation Glycogen accumulation is indicative of polysaccharide storage disorders . The most well-known of these in humans is . Diabetes involves the inability to produce the hormone insulin, either at all, or in sufficient quantities. There is little evidence of Diabetes
20
Made with FlippingBook Publishing Software