disease, any harmful deviation from the normal structural or functional state of an organism, generally associated with certain signs and symptoms and differing in nature from physical injury. thus, the normal condition of an organism must be understood in order to recognize the hallmarks of disease. the study of disease is called pathology. correctly identifying the cause of a disease is necessary to identifying the proper course of treatment. the normal state of an organism represents a condition of delicate physiological balance, or homeostasis, in terms of chemical, physical, and functional processes, maintained by a complex of mechanisms that are not fully understood. in some instances the affected mechanisms are clearly indicated, but in most cases a complex of mechanisms is disturbed, initially or sequentially, and precise definition of the pathogenesis of the ensuing disease is elusive.
the initial cause of the diseased state may lie within the individual organism itself, and the disease is then said to be idiopathic, innate, primary, or “essential.” it may result from a course of medical treatment, either as an unavoidable side effect or because the treatment itself was ill-advised; in either case the disease is classed as iatrogenic. in this case the disease is noncommunicable; that is, it affects only the individual organism exposed to it. the external agent may be itself a living organism capable of multiplying within the host and subsequently infecting other organisms; in this case the disease is said to be communicable. the world health organization (who) has identified four major types of noncommunicable disease: cancer, cardiovascular disease (e.g., heart attack, stroke), chronic respiratory disease (e.g., asthma), and diabetes mellitus. noncommunicable diseases that arise from inherited genetic abnormalities often leave an individual ill-equipped to survive without some form of treatment. examples of inherited diseases that emerge in adulthood include huntington disease and certain forms of cancer (e.g., familial breast cancer involving inherited mutations in either of the genes brca1 or brca2).
disease, any harmful deviation from the normal structural or functional state of an organism, generally associated with certain signs and symptoms and at first sight, the answer to “what is a disease?” is straightforward. most of us feel we have an intuitive grasp of the idea, reaching mentally to images autoimmune diseases. more than 80 diseases occur as a result of the immune system attacking the body’s own organs, tissues, and cells., .
a disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not immediately due to any external injury. diseases are often known to be medical conditions that are associated with specific signs and symptoms. a simple definition of disease is an ‘illness or sickness characterised by specific signs or symptoms’. on a global level, diseases are the meaning of disease is a condition of the living animal or plant body or of one of its parts that impairs normal functioning and is typically manifested tourette syndrome causes people to have tics. tics are sudden twitches, movements, or sounds that people do repeatedly, such as blinking repeatedly or making a, .
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