Chronic obstructive pulmonary disease (COPD) is a lung disease in which the lungs are damaged, making it a tiresome job for the patient to breath in and out effectively. The airways branch out like an inverted tree with small air sacs (balloon-like) at the end of each branch known as alveoli. Normally they are pliable and springy in nature. It helps in balloon-like inflation & deflation of lung tissue while breathing in and out respectively. COPD causes lungs to lose this elasticity and become flaccid so the amount of air that can go in and out decreases. More mucus secretion, inflamed wall thickening and lost elasticity contribute to this inefficiency.
Smoking is the main and most common cause of COPD while inhaling other types of irritant substances like: pollutants, chemicals, metals or dust also leads to the condition.
The very first symptom is often coughing sputum. Bronchitis is one part of the disease resulting in thickened and inflamed walls with mucus production. Coughing is the outcome. Emphysema is another part involving the collapse of the alveoli which affects the process of gas exchange. It results in dropped blood O2 levels and then CO2 is raised causing acidosis.