The respiratory system is made up of both the lower and upper respiratory systems. The lower section is comprised of the bronchial tubes and lungs, while the upper portion consists of the mouth, throat, nose, and sinuses. Respiratory system infections may affect both areas, and are generally caused by bacteria or viruses. It is not uncommon for a lower respiratory infection to occur after, or as a complication of, one that infects the upper respiratory tract.
Upper respiratory infections are more common, and usually less serous, than those in the lower system. Most infections of the lower respiratory tract are caused by bacteria, while those in in the upper respiratory tract are caused by viruses. There are, however, several bacterial illnesses that can affect the upper respiratory area.
Symptoms of a lower respiratory infection include a continuous cough that produces green or yellow mucus, a fever, and chest pain when breathing. Lower respiratory infections will typically also cause a person to have difficulty breathing, and he may experience a shortness of breath or wheezing. Infections of the upper respiratory system cause symptoms like coughing, facial pressure, and blocked nasal passages, either with or without a runny nose. A fever may also be present when the upper respiratory system is infected.
Common upper respiratory system infections include influenza and colds. Colds may cause a person to feel uncomfortable, but they are usually not a serious health threat and tend to clear up on their own without the need for a visit the doctor. Influenza can present serious symptoms and can develop into a health threat, especially in people with vulnerable immune systems, such as the very old or the very young. Both of these conditions are viral infections that do not respond to antibiotic treatment.
Bronchitis and pneumonia are the most common types of lower respiratory system infections, particularly among people who have pres-existing lung disease, smoke or are exposed to smoke. Many cases of these infections are caused by bacteria and can therefore be treated with antibiotics, but there are also viral strains of both illnesses. Lower respiratory system infections can cause significant health problems, and a person showing symptoms of these illnesses should seek medical treatment from a doctor.