1. Respiratory system
ا.م.د.بيداء حميد عبدالله

2. Pulmonary infection It can be caused by :
Viral, bacterial, fungal and mycoplasma infection.
Bacterial infection:
Bacterial invasion of the lung parenchyma will cause an exudative solidification (consolidation) of the lung tissue.
This is called (bacterial pneumonia).

3. Pathogenesis:
Normal lung is FREE from bacteria due to the presence of defense mechanisms:
Nasal clearance :by sneezing, blowing& mucous secretion.
Trachiobronchial clearance: by mucociliary action in which the foreign particles are either swallowed or expectorated
Alveolar clearance: by the alveolar macrophages  lymphatic circulation.

4. Pneumonia results whenever these defense mechanisms are impaired or the host resistance get lowered (chronic diseases, immune deficiency, leucopenia).
These clearing mechanisms can be interfered with e.g:
Loss or suppression of cough reflex (coma, anesthesia) , this may  gastric aspiration.

5. 2. Injury to the mucociliary apparatus e
2 . Injury to the mucociliary apparatus e.g cigarette, inhaled hot or corrosive gases,viral diseases or genetic diseases (immotile cilia syndrome).
3 . Interference with phagocytosis.
4 . Pulmonary congestion and pulm. Edema.
5 . Accumulation of secretion e.g cystic fibrosis& bronchial obstruction.

6. Etiology : We have TWO types of pneumonia : 1- Bronchopneumonia
Caused by staphylococcus, streptococcus, pneumococcus, hemophilus influenzae.
The consolidation is patchy.
Occur in infancy and old age groups caused by low resistance.
Can complicate long term heart failure

8. Bronchopneumonia

9. 2 . Lobar pneumonia
90-95% are caused by pneumococci.
Others are klebsiella pneumonia , staphylococcus, strept., H. influenza.
The consolidation involves a portion of a lobe or the whole lobe.

10. Lobar pneumonia

11. Morphology of lobar pneumonia:
There are four stages of evolvement of lobar pneumonia , they are:
Stage of congestion
Stage of red hepatization
Stage of grey hepatization
Stage of resolution.

12. Congestion stage Grossly: the lung is heavy and red in color. Mic.:
Alveolar vascular congestion
Intra-alveolar fluid with neutrophil + bacteria .

13. Red hepatization Grossly: red, firm, airless, look like a liver. Mic.:
The inflammatory exudate composed of RBC+ neutrophil+ fibrin.

14. Red hepatization

15. Grey hepatization Grossly: grey –brownish , dry surface. Mic.:
The exudate is composed of fibrin+ WBC which is called (fibrino-suppurative) exudate.

16. Early (organization) gray hepatization

17. Gray hepatization

18. Resolution stage
The exudate undergo enzymatic digestion formation of granular debris, that is either resorbed & ingested by the macrophages or expectorated and coughed up.

19. Morphology of Bronchopneumonia
Grossly: the well developed lesion is 3-4 cm , red /yellow, slightly elevated.
Mic.:
The consolidating area shows acute suppurative inflammation rich in neutrophils , filling the bronchi, bronchioles, & adjacent alveolar spaces.