Diseases :: essays papers

DiseasesDiseases argon any harmful change that interferes with the normalappearance, structure, or function of the body or any of its parts.Since time immemorial, disease has played a role in the history ofsocieties. It has affected and has been affected by economicalconditions, wars, and natural disasters. An epidemic of influenza thatswept the globe in 1918 killed between 20 million and 40 millionpeople. Within a few months, to a greater extent than 500,000 Americans diedmore thanwere killed during World War I (1914-1918), World War II (1939-1945),the Korean War (1950-1953), and the Vietnam War (1959-1975) combined.Diseases have diverse causes, which can be classified into twobroad groups communicable and noncommunicable. Communicablediseases can spread from one person to another and be caused bymicroscopic organisms that invade the body. Noncommunicable diseasesare not communicated from person to person and do not have, or are notknown to involve, infectious agents. Some d iseases, such as the commoncold, and practise on suddenly and last for no more than a few weeks. Otherdiseases, such as arthritis, are chronic, consistent for months oryears, or reoccur frequently. every(prenominal) disease has certain characteristic effects on the body.Some of these effects, include fever, inflammation, pain,fatigue, dizziness, nausea, and rashes, are evident to the patient.These symptoms offer important clues that help doctors and other health dispense professionals make a diagnosis. Many times, the symptoms point toseveral possible disorders. In those cases, doctors rely on medicaltests, such as blood examinations and X rays, to support thediagnosis.Communicable diseases are caused by microscopic organisms.Physicians refer to these disease-causing organisms aspathogens. Pathogens that infect humans include a wide variety ofbacteria, viruses, fungi, protozoans, and parasitic worms. Also, ithas been theorized that some proteins called prions may causeinfectious diseases.Bacteria are microscopic single-celled organisms at least 1micron long. Some bacteria species are harmless to humans, moreare beneficial. But some are pathogens, including those that causecholera, diphtheria, leprosy, plague, pneumonia, strep throat, tetanus,tuberculosis, and typhoid fever. The bacteria that are harmless andlive in or on you are called resident bateria.Viruses are tens or hundreds of times smaller than bacteria.They are not cellular, but consist of a core of geneticmaterial surrounded by a protective coat of protein. Viruses are ableto survive and reproduce only in the living cells of a host. Once avirus invades a living cell, it directs the cell to make new virusparticles. These new viruses are released into the surrounding tissues,and seek out new cells to infect.