Diseases, Degenerative

General Degenerations

Many types of degenerative diseases are not tissue specific, affecting many different tissue types in the body. One such disease is dystrophic degeneration, in which the body as a whole degenerates as a result of poor nutrition. This is usually associated with various psychological eating disorders such as anorexia nervosa and bulimia. The malnutrition associated with these diseases may also lead to other degenerations, such as atrophie pulp degeneration, in which the pulpal cells in dental pulp degenerate. A classical systemic degeneration is senile degeneration, in which the age of the patient has caused bodily and mental degenerations, and the toll of time causes widespread changes. This includes the atrophy of muscles, declining sight (macular degeneration), dulling senses, a decrease in mental retention and abilities, and fibrous and atheromatous changes. Everyone experiences senile degeneration to some degree as they age and their muscles weaken through time; however, the rate of degeneration depends on many factors, including diet, exercise, familial history, and lifestyle.

The immune system also plays a large role in the degeneration of cells. Cloudy swelling degeneration occurs during the local inflammatory response of the immune system. Here, the cells take on water as the macrophages and fluids move to the offended site. This may also be called vacuolar degeneration, as the vacuoles tend to grow as well. If the injury has somehow affected the metabolism of the cell, this cloudy swelling degeneration may persist, but it generally goes away with time. A severe form of cloudy swelling degeneration is hydropic degeneration, in which water droplets can be visualized within the cell. This is also known as ballooning degeneration. Following the immune response, the body immediately begins the rebuilding process. The plasma protein fibrin migrates to the offended site and begins to aggregate to form a clot. This process is known as fibrous degeneration, or fibrosis. This is considered a degenerative process, as a lower form of tissue is replacing a higher one. This fibrous tissue is what forms scars and is a normal part of the healing process. However, when fibrosis becomes excessive, it can lead to many problems within the body. For example, if fibrin is activated within the bloodstream, it may form a blood clot within the vessel, which may travel as an embolus to the heart, causing a myocardial infarction (heart attack), or to the brain, causing a cerebrovascular accident (stroke).

If tissue is not repaired, it can lead to death of the tissue, or necrosis. Necrosis is characterized by several different degenerations, including the aforementioned fibrous degeneration. Another type of necrotic degeneration is caseous degeneration, or caseation. The soft, cheesy appearance of the necrotic tissue characterized by this degeneration earned it the name of “cheesy degeneration” as well. This is a common degeneration found in the lungs of tuberculosis patients. Necrosis of striated muscle is known as Zenker's degeneration, or waxy degeneration, in which the muscle cells die and take on a glassy appearance. This often is the result of a severe infection, such as typhoid fever.

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