Asthma - causes, symptoms, diagnosis, treatment, pathology

Asthma involves chronic airway inflammation leading to bronchoconstriction. Triggers initiate a Type 2 helper (Th2) immune response, releasing cytokines like IL-4 and IL-5. This results in IgE production, mast cell degranulation, and eosinophil activation, causing immediate smooth muscle spasms and increased mucus secretion.

Initial inflammatory changes are reversible; however, chronic exposure leads to irreversible structural modifications, including scarring, fibrosis, and thickening of the basement membrane, permanently reducing airway diameter.

Asthma stems from genetic and environmental interactions, including the 'hygiene hypothesis.' Symptoms include wheezing, coughing, chest tightness, and dyspnea. Sputum may reveal Curschmann spirals and Charcot-Leyden crystals due to eosinophil breakdown.

Asthma is classified by symptom frequency and lung function testing (FEV1 and PEFR). Management includes environmental avoidance and pharmacological intervention, ranging from emergency bronchodilators for acute spasms to corticosteroids and long-acting agonists for persistent cases.