Diseases and Allergies Affecting the Human Gas exchange System
Do you know of someone who becomes ill when he or she eats a particular type of food, or when they are around certain pets? We say that such persons are allergic and the things that they eat are sensitive to are referred to as allergens. Pollen grains, spores, feather, animal fur or skin, certain foods and chemicals are some of the more common allergens.
Everyone is not allergic to these substances. It only affect those who have an inborn or inherited tendency to develop the allergy, which is about 10% of the population. When these substances enter the bodies of such persons (usually through breathing) they develop an allergic reaction or allergic attack. Sometimes the allergic reaction may be mild. For example, the skin may develop lumps that may disappear, without any treatment, after a few hours. In other cases, the reaction might be very serious, requiring medical treatment and even hospitalization. For example, someone might have extreme difficulty in breathing , as a result of an asthma attack brought on by exposure to certain allergens. Hay fever is another example of an allergic reaction.
A disease is caused when the normal functioning of the plant or animal is upset or changed by infections (e.g. bacteria, viruses), by environmental factors (e.g. poor nutrition, pollution) or because of in-born defects (e.g. a poorly functioning kidney). Lung cancer, tuberculosis (TB), bronchitis, pneumonia, pleurisy, emphysema, the common cold and influenza are all examples of diseases that affect the gas exchange system of human.