- Atopic (Allergic, Extrinsic) Asthma
| Inhaled allergens produce a type I hypersensitivity response with increased eosinophils seen in sputum and peripheral blood
| - Nonatopic (Intrinsic) Asthma
| Bronchoconstriction is triggered by infections, cold, and air pollutants, typically in middle-aged adults
| | Chronic Bronchitis | Chronic irritation of airways (smoking, air pollution) complicated by repeated infections leads to a persistent cough with sputum production for at least 3 months in at least 2 consecutive years. There is hypersecretion of mucus from hypertrophied submucosal glands with goblet cell hyperplasia
| | Emphysema | Destruction of the normal pulmonary acinar structure leads to dilation of distal airspaces
| - Centrilobular (Centriacinar)
| Predominantly the respiratory bronchioles of the proximal acinar structure are affected, sparing distal alveoli. Mostly seen in smokers. Upper lung fields are predominantly involved. Most common in smokers
| - Panlobular (Panacinar)
| All portions of the acinus are involved. Lower lung fields are predominantly involved. Can occur in association with alpah-1-antitrypsin deficiency
| - Paraseptal (Irregular)
| Focal scarring, often subpleural, results in dilation of airspaces
| | Bronchiectasis | Chronic infection leads to destruction and dilation of bronchi
| - Localized
| Focal obstruction from a neoplasm, enlarged lymph nodes, or an inhaled foreign body leads to stasis distal to the obstruction and consequent infection
| - Diffuse
| A congenital condition such as cystic fibrosis, immotile cilia, or Kartagener's syndrome affects all airways and diminishes their normal functioning with mucus obstruction
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