2.03 - Pathology Of Pneumonia Flashcards Preview

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Flashcards in 2.03 - Pathology Of Pneumonia Deck (21):

Describe the histology of the Trachea

Mucosa - Epithelial layer: Pseudostratified ciliated columnar epithelium and also goblet cells (get fewer and fewer as move down respiratory tract)
Submucosa --> seromucus layer
Tracheal cartilage layer --? hyaline cartilage, 12-14 cartilage rings important in maintaining the structure


Describe the histology of a bronchus

Mucosa- epithelial layer (ciliated pseudostratified columnar epithelium with goblet cells), lamina propria
Discontinuous smooth muscle layer (becomes more prominent at bronchioles)
Submucosa- seromucinous glands
Discontinuous plates of cartilage


Describe the histology of a bronchiole

Mucosa - Epithelial layer (ciliated columnar/cuboidal epithelial cells as well as non-ciliated Clara cells)
Smooth muscle layer prominent
Lost cartilage layer
Adventitia- fuses with surrounding tissues helping to keep all structures in the respiratory tree in place


How does a respiratory bronchiole differ from a terminal bronchiole?

Terminal bronchioles purpose is to allow passage of air, so not gas transfer takes place. Respiratory bronchioles often have alveoli coming of their walls so can aide in gas transfer


What are the types of cells in an alveoli?

Type 1 pneumocyte - gas exchange
Type 2 pneumocyte - secrete surfactant
Alveolar macrophages - within alveolus, usually can see material in cytoplasm
Also, between alveoli are pores that help to keep them open if bronchiole is blocked, physical benefit and supplies collateral airflow from alveolus next door


What is the function of acute inflammation?

Fluid dilutes toxins
Fibrinogen converted fibrin
o Immobilises infectious organisms
o Scaffolding for the migration of neutrophils
Immunoglobulins may neutralize infectious organisms
o Phagocytoseandkillorganisms
o Secrete enzymes initiating lysis of dead cells


How can pneumonia be classified?

Causative agent
Clinical setting (e.g. community acquired, hospital acquired)
Mechanism (e.g. aspiration)
Gross anatomic distribution (bronchogenic, lobar)


Describe bronchopneumonia

Patchy consolidation of the lung
Extension of a preexisting bronchitis
Common at the extremes of life


Describe lobar pneumonia

Acute infection of an entire lobe (bacterial, tissue consolidation and then leakage of fluid into tissues)
Onset abrupt
Now infrequent due to antibiotic treatment


What are the four stages of lobar pneumonia?

Red Hepatisation
Grey Hepatisation


Describe the congestion phase of lobar pneumonia

Enlarged lobe
Capillaries dilated and congested with blood
Air spaces filled with pale fluid
Occasional bacteria


Describe the red hepatisation phase of lobar pneumonia

Looks solid and not sponge like, very vascular and dilated
Cut surface is dry and red, resembles liver
Increased numbers of neutrophils
Fluid which contained fibrinogen has clotted in the alveolar spaces
Bacteria is more numerous


Describe the grey hepatisation phase of lobar pneumonia

Still looks solid due to inflammatory exudate
Several days into inflammation, loss of the red colour after 2-3 days
Starts at hilum and moves out
Vascular response decreasing, migration of large numbers of neutrophils
Decrease in capillary congestion
Decreased blood flow through the unventilated lobe


Describe the resolution phase of lobar pneumonia

Bacteria/inflammatoryexudatedigestedby enzymes and return to structure there before
Liquefaction of the previously solid exudate
Fibrinolytic enzymes
Apoptosis of neutrophils
Fluid contents removed
Takes several weeks


What are the others types (beside bacterial) of pneumonia?

Viral (respiratory syncytial virus, cytomegalovirus)
Fungal (pneumocystis)


Describe the pneumonia caused by respiratory syncytial virus

Winter epidemics
Children under 6 months particular prone URT --> LRT
Bronchilotis and pneumonia
Destrution of bronchiolar epithelium
Epithelium debris, mucus plugs and fibrin
Giant cells


Describe the pneumonia caused by cytomegalovirus

Herpes virus
Newborns and immunocompromised
Transplant recipients
Chronic interstitial pneumonitis
Classic intra-nuclear and cytoplasmic inclusions


Describe aspiration pneumonia

Aspiration pneumonia favoured by
Loss of consciousness
Suppression of cough reflex
Poor oral hygiene

Affects dependent parts of the lung
Apical lower lobe
Basal upper lobe

Bronchopneumonia pattern

Bacteria responsible are the flora of the URT
Florid peri-bronchial consolidation
Particles of undigested food present
Foreign body giant cells


Describe lipid pneumonia

Lung generates lipid within surfactant (decreases alveolar surface tension)
Surfactant cleared by alveolar epithelium and via the airways
Obstruction (foreign bodies, tumour) of airways leads to build up of lipid in macrophages


What are some complications of bacterial pneumonia (lobar and broncho)

Broncho pneumonia
o Healing by fibrosis
o Abscess formation

Lobar pneumonia
o Pleuritis
o Empyema (build up of pus in pleural cavity)
o Abscess formation
o Haemotogenous seeding
o Death


What are some signs and symptoms of bacterial pneumonia?

Pleuritic chest pain
Increased respiratory rate