ABSTRACT
Asthma and COPD are referred to as obstructive lung diseases. The respiratory tract facilitates the movement of air in and out of the lungs and is made up of airways (passages) called bronchi and smaller bronchioles, terminating in small air sacs (alveoli) where oxygen and carbon dioxide between lungs and blood are exchanged. The process of breathing drives air through the airways, and in health, little effort is required as there is no obstruction to flow. A number of factors can contribute to airway obstruction, and in diseases such as asthma and COPD it is inflammation of the delicate inner lining of the airways. Irritation of this inner lining (respiratory epithelium) results in a great number of inflammatory cells (e.g. neutrophils and eosinophils) contributing to increased narrowing as a result of tissue swelling and muscle spasm. This narrowing of the airways makes the work of breathing much harder and there is increased awareness of the effort involved with each breath. We will consider asthma and COPD separately.
