Pathology of obstructive airway diseases Flashcards
Describe the effect of obstructive lung diseases on physiology.
There is AIRFLOW LIMITATION
Peak Expiratory Flow Rate (PEFR) is reduced
FEV1 is REDUCED
FVC may be reduced
FEV1 is less than 70% of FVC
What is COPD also known as?
Chronic obstructive pulmonary disease is better also known as emphysema and chronic bronchitis.
Describe the major pathological features of
- asthma
Asthma - Type 1 hypersensitivity, Inflammation of airways lining the mucosa due to activation of mast cells by IgE releasing a range of chemical factors. Swelling of mucosa due to inflammation combined with contraction of smooth muscle causes constriction of airways.
Describe the reversibility of bronchial asthma.
Generally considered to be REVERSIBLE airways obstruction either spontaneously or as a result of medical intervention
Bronchial smooth muscle contraction and inflammation can be modified by drugs
Describe the major pathological features of
- chronic bronchitis
Chronic Bronchitis is defined clinically:
Cough productive of sputum most days
in at least 3 consecutive months
for 2 or more consecutive years
Describe complicated chronic bronchitis
‘Complicated chronic bronchitis when sputum turns mucopurulent (acute infective exacerbation) or FEV1 falls
Describe morphological changes in chronic bronchitis.
Large Airways
Mucous gland hyperplasia
Goblet cell hyperplasia
Inflammation and fibrosis is a minor component.
Small Airways
Goblet cells appear
Inflammation and fibrosis in long standing disease.
Describe the major pathological features of
- Emphysema
Pathological Definition
Increase beyond the normal in the size of airspaces distal to the terminal bronchiole arising either from dilatation or from destruction of their walls and without obvious fibrosis.
Define what an acinus is.
A small region of the lung supplied from air in the terminal bronchioles.
Describe the types of emphysema
Centri-acinar Emphysema:
Begins with bronchiolar dilatation. Then alveolar tissue is lost
Panacinar Emphysema:
Tissue destruction is uniform throughout the acinus.
Periacinar Emphysema:
Enlarged airspaces (bulla) along the edge of the acinar unit, but only where it abuts against a fixed structure such as the pleura or a vessel.
Describe pathology of emphysema
SMOKING
Protease - Antiprotease imbalance
Ageing
Alpha-1-antitrypsin deficiency
loss of alveolar attatchments
Describe the effect of an antitrypsin deficiency by comparison to a normal individual.
Describe the reversibility of COPD.
Traditionally airway obstruction in COPD is considered irreversible.
However smooth muscle tone and inflammation in the small airways respond to pharmacological intervention.
Describe the loss of alveolar attachments in emphysema.
Alveolar attachments connect the alveolar wall to the small airway essentially holding it in place. Loss of these in emphysema is considered abnormal.
Describe the symptoms and clinical patterns of asthma, and show how this affects the
O2 alveolar gas.
Constriction of the airways causes less air to reach the lungs therefore less oxygen to the alveoli.
