Respiratory System Lesson: Pneumonia & Tuberculosis
Lesson Overview
- What Is the Respiratory System and How Does It Work?
- Pneumonia: Pathophysiology, Causes, and Symptoms
- Tuberculosis: Pathophysiology, Symptoms, and Types
- Comparing Pneumonia and Tuberculosis
- Diagnostic Methods
- Insights with Q&A
- Treatment Approaches
- Preventive Measures
- Oxygen Toxicity in Respiratory Care
- Terminologies to Remember
- Key Takeaway
Imagine struggling to breathe, not from running a marathon, but from something as invisible as bacteria in the air. Respiratory infections like pneumonia and tuberculosis (TB) are major contributors to global illness and mortality.
Understanding how these diseases disrupt normal lung function is essential, especially for aspiring healthcare students. This lesson explores the respiratory system's structure, how pneumonia and TB affect it, and the essential strategies to diagnose, treat, and prevent these conditions.
What Is the Respiratory System and How Does It Work?
The respiratory system consists of the airways, lungs, and alveoli that enable oxygen intake and carbon dioxide removal.
Key Functions:
- Ventilation: Movement of air in and out.
- Gas Exchange: Occurs in the alveoli.
- Protection: Mucus and cilia trap pathogens.
Disruption in any part can result in infections like pneumonia or TB, which reduce the lungs' efficiency.
Pneumonia: Pathophysiology, Causes, and Symptoms
Definition:
Pneumonia is an infection that inflames the alveoli, often filling them with fluid or pus.
Causes:
- Bacteria: Streptococcus pneumoniae (most common)
- Viruses: Influenza, RSV
- Fungi: In immunocompromised individuals
Pathophysiology:
Infection triggers alveolar inflammation → exudate formation → impaired oxygen exchange.
Common Symptoms:
| Symptom | Description |
| Fever and chills | Often sudden and high (≥102°F) |
| Productive cough | Yellow/green or rust-colored sputum |
| Chest pain | Sharp, worsens with breathing |
| Dyspnea | Shortness of breath |
| Confusion | Especially in the elderly |
Tuberculosis: Pathophysiology, Symptoms, and Types
Definition:
TB is a chronic infectious disease caused by Mycobacterium tuberculosis, transmitted via airborne droplets.
Stages:
- Latent TB: Inactive, asymptomatic, not contagious
- Active TB: Symptomatic and contagious
Pathophysiology:
The bacteria survive inside macrophages → granuloma (tubercles) formation → caseous necrosis in active TB.
Key Symptoms of Active Pulmonary TB:
| Symptom | Notes |
| Chronic cough | >3 weeks, possibly with blood (hemoptysis) |
| Night sweats | Profuse and regular |
| Weight loss | "Wasting" appearance |
| Low-grade fever | Often in the evening |
Comparing Pneumonia and Tuberculosis
| Feature | Pneumonia | Tuberculosis |
| Onset | Sudden, acute | Gradual, chronic |
| Common cause | Strep. pneumoniae | Mycobacterium tuberculosis |
| Fever | High, acute | Low-grade, persistent |
| Cough | Productive | Dry, later hemoptysis |
| Contagious? | Sometimes | Highly (if active) |
| Diagnostic method | Chest X-ray | Sputum culture (definitive) |
| Duration of treatment | 5–10 days | 6–12 months or more |
Diagnostic Methods
Pneumonia Diagnosis:
- Chest X-ray: Primary tool for visualizing consolidation.
- Sputum culture: Identifies causative bacteria.
- Physical exam: Crackles, bronchial breath sounds.
- CBC and oxygen levels: Assess severity.
TB Diagnosis:
- PPD skin test (Mantoux): Measures delayed-type hypersensitivity (≥10mm induration = positive for most).
- Chest X-ray: Looks for upper lobe lesions or cavitations.
- Sputum culture: Definitive test for TB.
- IGRA (blood test): For people previously vaccinated with BCG.
Insights with Q&A
Q: Which test is definitive for TB?
Answer: Sputum culture
Why? Confirms the presence of Mycobacterium tuberculosis directly.
Q: Why is a chest X-ray done after a positive Mantoux test?
Answer: To assess the extent of lesions, not to confirm the infection.
Q: A client with positive PPD but no symptoms should receive?
Answer: Isoniazid (300 mg daily) for 9–12 months to prevent progression to active TB.
Q: TB patient's sputum remains positive after 2 months-what does this indicate?
Answer: Treatment failure or noncompliance.
Q: Breath sound heard in pneumonia over consolidated areas?
Answer: Bronchial breath sounds (normally only over trachea).
Q: Atypical pneumonia sign in the elderly?
Answer: Altered mental status and dehydration, not cough or fever initially.
Treatment Approaches
Pneumonia:
- Antibiotics (e.g., amoxicillin or macrolides)
- Oxygen if dyspnea or low saturation
- Supportive care: Fluids, rest, chest physiotherapy
Tuberculosis:
| Phase | Medications Used | Duration |
| Intensive | INH + Rifampin + Pyrazinamide + Ethambutol | 2 months |
| Continuation | INH + Rifampin | 4–10 months |
Monitoring: Monthly sputum smears, liver function- DOT (Directly Observed Therapy): Ensures adherence
Preventive Measures
Pneumonia Prevention:
- Vaccines: Pneumococcal, influenza
- Oral hygiene: Prevent aspiration pneumonia
- Avoid smoking: Preserves lung defense mechanisms
Tuberculosis Prevention:
- BCG vaccine (where applicable)
- Screening and treating latent TB
- Isolation of active TB cases
- Adequate ventilation and N95 mask use in healthcare settings
Take This Quiz:
Oxygen Toxicity in Respiratory Care
Prolonged high-flow oxygen can damage lung tissue. It:
- Reduces alveolar surface area for gas exchange
- Causes pulmonary edema and inflammation
Clinical insight: Always use the lowest effective FiO₂ for the shortest time necessary.
Terminologies to Remember
| Term | Meaning |
| Latent TB | Infected, asymptomatic, not contagious |
| Active TB | Infected, symptomatic, contagious |
| Tuberculin Converter | Recent PPD test turned from negative to positive (new infection) |
| Reactivation TB | Latent TB turning active due to immunosuppression |
Key Takeaway
Pneumonia and tuberculosis are both serious respiratory conditions with different pathophysiologies, diagnostic approaches, and management strategies. While pneumonia tends to present acutely and respond to short-term treatment, TB is a chronic disease demanding prolonged therapy and strict monitoring. Mastering the distinctions between these diseases, recognizing their classic presentations, and understanding the diagnostic logic will enable students to confidently tackle related questions in exams-and apply this knowledge in real-world clinical settings.
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