For many of us, diseases like smallpox, polio, measles and leprosy sound like ailments from the past. Thanks to the hard work of clinical researchers, we now know how to treat and prevent many deadly diseases. In fact, many diseases are on the verge of being eradicated altogether. While modern medicine has focused on prevention and long-term symptom management, scientists are constantly striving toward true cures.
Disease is a condition of the body that disrupts normal chemical, physical and functional processes. The normal state of an organism is a delicate physiological balance (homeostasis) maintained by a series of mechanisms that are not fully understood. Disease occurs when these mechanisms are broken down, leading to a disruption of homeostatic control.
Different types of infectious agents cause markedly different diseases. Some spread from a focus of infection by direct extension through the lymphatic system or by the bloodstream. Intracellular pathogens often spread by release of toxic protein toxins, which damage cells they infect. Some diseases are also caused by the immune response to the infectious agent; for example, autoimmune disorders such as Crohn’s Disease and Lupus occur when your immune system mistakenly attacks healthy tissue.
A defining characteristic of a disease is its signs and symptoms, which are characteristic qualities of the diseased condition as observed by an observer. Observers are usually physicians or medical patients, but they may also be members of the public who have experienced a disease. Signs and symptoms are elicited by the abnormal physiological processes that define the disease and reflect changes in internal body functions, including metabolic, biochemical and other pathways.
About the Author
