COPD stands for chronic obstructive pulmonary disease. There are 2 major diseases included in COPD: 1) chronic bronchitis, and 2) emphysema. In both, narrowed bronchi make it hard to exhale. In chronic bronchitis, enlargement of the mucous glands and too much mucus production contribute to the narrowing. In emphysema, narrowing comes from damage to the bronchi themselves and is more severe. Inflammation triggered by inhaled irritants also contributes to COPD.