Pathology of respiratory system

 Pathology of the Respiratory System

🔹 Overview:

The respiratory system can be affected by infections, obstructions, inflammatory diseases, neoplasms, and autoimmune conditions. Pathology can occur in any part—from nasal passages to alveoli.

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🔬 1. Inflammatory and Infectious Diseases

🔸 Upper Respiratory Tract Infections (URTI)

Common cold: Caused by rhinoviruses

Pharyngitis, tonsillitis: Often viral or streptococcal

Sinusitis: Bacterial or fungal

🔸 Lower Respiratory Tract Infections (LRTI)

Bronchitis:

Inflammation of bronchi

Commonly viral; chronic form seen in smokers (COPD)

Pneumonia:

Infection of alveoli

Types:

Lobar pneumonia: Entire lobe affected (Streptococcus pneumoniae)

Bronchopneumonia: Patchy areas (mixed organisms)

Atypical pneumonia: Mycoplasma, viruses

Tuberculosis (TB):

Caused by Mycobacterium tuberculosis

Granulomatous inflammation with caseous necrosis

Seen on chest X-ray as cavities or nodules

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🫁 2. Obstructive Lung Diseases

🔸 Chronic Obstructive Pulmonary Disease (COPD)

Includes chronic bronchitis and emphysema

Symptoms: Chronic cough, sputum, dyspnea

🔸 Asthma

Reversible airway obstruction

Triggered by allergens, exercise, cold air

Pathology: Smooth muscle spasm, mucus plugging, inflammation

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🧫 3. Restrictive Lung Diseases

🔸 Pulmonary Fibrosis

Thickening and scarring of lung tissue

Causes: Idiopathic, occupational (asbestosis, silicosis), drugs

🔸 Sarcoidosis

Granulomas in lungs and lymph nodes

Immune-mediated, unknown cause

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⚠️ 4. Vascular Disorders

🔸 Pulmonary Embolism (PE)

Blood clot in pulmonary artery (often from deep veins in legs)

Sudden chest pain, dyspnea, hemoptysis

🔸 Pulmonary Hypertension

High pressure in pulmonary arteries

Causes: Chronic lung disease, heart conditions

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🧬 5. Neoplastic Diseases

🔸 Lung Cancer

Most common: Non-small cell carcinoma (NSCLC)

Subtypes: Adenocarcinoma, Squamous cell carcinoma

Small cell lung cancer (SCLC) – More aggressive

Risk factor: Smoking

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🦠 6. Other Conditions

🔸 Pleural Effusion: Fluid in pleural space

Causes: Infection, heart failure, malignancy

🔸 Pneumothorax: Air in pleural space → lung collapse

🔸 Cystic Fibrosis: Genetic disorder, thick mucus blocks airways

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🧪 Diagnostic Methods:

Chest X-ray, CT scan

Sputum analysis

Pulmonary function tests

Bronchoscopy

Biopsy

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