The lower respiratory system

1. The lower respiratory system

2. Respiratory system

3. Gross anatomy of lung and thorax. b: Microscopic anatomy of bronchial wall. C: View of terminal airway and alveoli. d: Alveolar structure.

4. Diseases of the lower respiratory system • Inflammatory: Bronchitis, Bronchiolitis, pneumonia • Chronic obstructive airways ( pulmonary) diseases: Chronic bronchitis, emphysema, asthma and bronchiectasis. • Diseases of the lung: lung collapse, ARDS • Diseases of the pleura: pleural effusion and pneumothorax

5. Inflammatory disordersBronchitis • Inflammation of bronchi • Acute bronchitis is caused by irritant chemical or by an infection • Acute infective bronchitis : • Initiated by viruses such as respiratory syncytial virus followed by bacterial invasion. Streptococcus pneumoniae and Haemophilus influenzae • Acute bronchitis is characterized by abundant mucoid secretion.

6. Bronchiolitis • Inflammation of bronchioles. • There are three main types: • Primary bronchiolitis: It is usually caused by viruses especially RSV. It is most commonly seen in infants. Resolution is usual. A minority of patients develop bronchopneumonia • Follicular bronchiolitis: It is seen in patients with rheumatoid arthritis. Lymphoid aggregates compress the airways. • Bronchiolitis obliterans: Can occur from a number of diseases and is characterized by the obliteration of bronchiolar lumina by masses of inflammatory exudates.

7. Follicular Bronchiolitis

8. Bacterial pneumonia • Inflammatory condition of the lung characterized by consolidation of the pulmonary tissue. • Pathogenesis: The causative organism infect the lung parenchyma inflammatory exudates within the alveolar spaces with consequent consolidation. • Pneumonia results whenever defense mechanisms to clear any inhaled microorganism are impaired.

9. Bacterial pneumonia Bronchopneumonia Lobar pneumonia

10. Stages of lobar pneumonia 1- congestion 2- Red hepatization 3- Gray hepatization 4- Resolution

11. Atypical pneumonia • The term atypical is used when the inflammatory changes in the lungs are confined to the alveolar septa and interstitium without significant alveolar exudate. • Aetiology: • In immunocompetent individuals the causes are: viruses (influenza, RSV or adenoviruses), Bacteria (Legionella pneumophilia, mycoplasma) Coxiella burnetii (Q fever) • In immunocompromised individuals the causes of atypical pneumonia are: Viruses (CMV, varicella, measles), Bacteria (Pneumocystis carinii, Chlamydia) Fungi (Candida, Aspergillus).

12. Chronic obstructive airways (pulmonary) diseases COPD • A group of diseases in which there is an increase in resistance to air flow, due to partial or complete obstruction at any level of the respiratory tree. • The incidence and severity of COPD are strongly correlated with air pollution and smoking. • The major obstructive disorders are: Chronic bronchitis, emphysema, asthma and bronchiectasis.

13. 1- Chronic bronchitis • Repeated episodes of acute bronchitis which may lead to respiratory failure and may cause death. • Clinically defined as the presence of a productive cough lasting at least 3 months and occurring annually for at least 2 years. • The condition tends to affect middle-aged men who are smokers. • Pathogenesis: Irritant such as tobacco smoke, cause 2 main abnormalities, which lead to airway obstruction • Increase in size of submucosal glands. Hypersecretion of mucus mainly in large airways which results in mucus plugging and overproduction of sputum • A respiratory bronchiolitis affecting the smaller airways

14. 2- Emphysema • abnormal permanent enlargement of airspaces distal to the terminal bronchiole, accompanied by the destruction of their walls. • Pathogenesis: Related to an imbalance of protease-antiprotease activity in the lung. Patients with alpha-1 antitrypsin deficiency have a relative increase in protease activity. • Cigarette smokers tend to have more neutrophilis and macrophages recruited to the alveolar parenchyma, compared with non-smokers. These two cell types are the major source of proteases and elastases in the lung.

16. 3- Asthma • Sudden episodes of broncho -constriction with dyspnoea, coughing and wheezing. • There are 2 basic types: • Extrinsic asthma: induced by exposure to extrinsic allergen and is mediated by type –І hypersensitivity reaction. e.g. Atopic allergic asthma, occupational asthma • Intrinsic asthma: indiced by pulmonary infection, ingestion of aspirin, cold and stress. Not mediated by immunological reaction.

17. Atopic allergic asthma • Typically starts in childhood • There is often a family history of asthma or other atopic condition e.g. hay fever or eczema • Triggered by IgE type–І hypersensitivity reaction to inhaled allergens • A number of chemical mediators are involved e.g. Histamine, prostaglandin, leukotrienes, platlet- activating factor, tumor necrosis factor, chemokines and various interleukins • Morphological changes seen in the lungs in severe asthma: • Mucous plugging of bronchi • Oedema and inflammation of the bronchial walls • Over inflation of the lungs distal to the obstruction • Mucous gland hypertrophy • Bronchial wall smooth muscle hypertrophy and contraction

18. 4- Bronchiactiasis • Irreversible dilation of portions of the bronchi or bronchioles • Characteristics: • - Involved bronchi are dilated, inflamed, and easily collapsible. • - Airflow obstruction and impaired clearance of secretions. • - Patients suffer from cough with large amount of foul- smelling sputum. • Aetiology: Both obstruction and infection are causes for development of bronchiactiasis

19. Bronchiactiasis