Pathology of Respiratory Tract and Pulmonary Infection Flashcards
3 factors that causes lung infection
- micro-pathogenicity (primary, facultive/opportunistic)
- capacity to resist infection
- population at risk
organisms that causes epiglottis
- HI type B
- group A beta haemolytic streptococcus
- parainfluenza virus type 4
4 respiratory tract defence mechs
- macrophage mucociliary escalator system
- general immunity
- secretions
- URT filter (nasal cavity –> turbulent air flow, nose hair)
describe the macrophage mucociliary escalator system
- macrophage roams the surface of the resp system and phagocytose any pathogen it comes across
- jumps onto the mocociliary escalator of mucous being pushed up by ciliated epithelium cells
- pushed to the top of the lungs to be removed by cough reflex (or swallow)
types of epithelium in trachea+bronchi, bronchioles, alveoli
nasal cavity –> bronchi: pseudostratified columnar epithelium + goblet cells (consists primarily of columnar ciliated cells)
bronchioles: ciliated simple cuboidal epithelium
alveoli: simple squamous epithelium
mech of influenza infections (related to the mucociliary escalator)
when there is viral infection, normal epithelium with cilia that can move mucous will be replaced with useless virus invaded cells –> no escalator system –> secretions and pathogen build up in the lungs with no exit –> more bacterial infections on top of the flu
if you happen to have another obstruction, like a tumor, that blocks the exit of the secretions, even if the escalator system works you would end up with the same result because you can’t expel the dirty stuff
Aetiological classification of pneumonia
- community vs hospital acquired
- typical/atypical
- aspiration pneumonia
- recurrent pneumonia
- microbiology (which strain)
- hypostatic (water accumulation at the base of the lungs –> infection)
- obstructive, retention, endogenous lipid
causes of recurrent pneumonia
- local pulmonary obstruction
- local pulmonary damage
- general lung diseases (COPD, asthma)
- non-resp diseases (HIV, immunocompromised)
3 patterns of pneumonia based on location
- bronchopneumonia
- segmental pneumonia
- lobar pneumonia
bronchopneumonia vs lobar pneumonia
BRONCHOPNEUMONIA:
- localized infection only around the bronchioles
- rarely seen in healthy people, usually have underlying health conditions
- bilateral and normally seen in lower regions
LOBAR PNEUMONIA:
- not localized, occupies the whole lobe up until the barrier (pleura) is reached
- vigorous inflammatory response
- primary pathogens affecting young, fit people
complications of pneumonia
- empyema
- pleurisy
- lung abscesses
- bronchiectasis
describe empyema
- infection –> pus –> accumulation –> fibrosis
- cryptogenic organizing pneumonia and scar tissue formation around the inflammation –> hardened tissue that is confused with lung cancer
- may need to be surgically removed
describe pleurisy
- fibrous pleural exudate
- complicates the infection because pleura is affected
describe lung abscess and its possible causes
- death of infected tissue –> space for pus accumulation
CAUSES:
- obstruction of bronchus, like tumor
- aspiration
- organism (staph aureus, klebsiella, pneumococci, staphylococcus results in cheese like abscesses)
- metastasis in pyemia (blood)
describe bonrchiectasis
- pathological dilation of bronchi
- localized to the bronchi, but affects the whole lung and therefore no surgical treatment
- possibly haemoptysis if there is bleeding from the artery supplying the main bronchi
