The human respiratory system includes trachea, bronchi, bronchioles, lungs, and diaphragm. Oxygen that we breathe in and carbon dioxide that we breathe out is exchanged in the alveoli (air sacs) inside the lungs.
Bronchitis is a respiratory problem where the lining of the bronchial tubes (it carries air to and from the lungs) becomes inflamed or swells. The reason can be an infection or the person’s lifestyle. People with bronchitis have reduced ability to breathe in air and oxygen into their lungs; they also face discomfort because of the deposition of heavy mucus or phlegm in their airways.