Definition — 1 mark Definition of COPD Chronic and progressive airflow limitation 2. Etiology / Risk Factors — 2 marks Smoking Biomass fuel exposure Occupational dust/fumes Air pollution Passive smoking Recurrent respiratory infections α₁-antitrypsin deficiency Genetic and developmental factors 3. Clinical Features — 2 marks Symptoms: Dyspnea Chronic cough Sputum production Wheezing Chest tightness Fatigue and reduced exercise tolerance Signs: Tachypnea Accessory muscle use Prolonged expiration Pursed-lip breathing Reduced breath sounds Hyperinflated chest Cyanosis in advanced disease 4. Pathophysiology — 4 marks Explain with flowchart: Smoking/irritants → chronic inflammation → airway narrowing + mucus hypersecretion + alveolar destruction → ↓ elastic recoil → expiratory airway collapse → air trapping → hyperinflation → V/Q mismatch → hypoxemia ± hypercapnia → pulmonary hypertension → cor pulmonale Include: Chronic bronchitis Emphysema Airflow obstruction Dynamic hyperinflation Respiratory muscle dysfunction V/Q mismatch explain detail created image