The lungs Flashcards
Type of epithelium lining the respiratory tree (except vocal cords)
Pseudostratified tall columnar ciliated epithelial cells.
Features of bronchi that bronchioles do not share
Cartilage and submucosal glands.
Epithelium covering vocal cords
Stratified squamous epithelium.
Other cells in the bronchi and trachea
Goblet cells
Submucosal glands
Neuroendocrine cells (bronchial only).
Structure of alveolar walls.
Type I and type II pneumocytes (synthesises surfactant).
Basement membrane and interstitial tissue.
Endothelial cells lining capillaries.
Congenital abnormalities of the lung
Pulmonary hypoplasia (due to lung compression in utero)
Foregut cysts.
Pulmonary sequestration.
What is pulmonary sequestration?
An area of lung without connection to airway system and abnormal blood supply arising from the aorta.
Types of atelectasis
Resorption
Compression
Contraction
Cause of resorption atelectasis
Obstruction (mucus plug, exudate, foreign body) of an airway leads to air resorption.
Mediastinum shift toward atelectic lung.
Which way does the mediastinum shift in compression atelectasis?
Away from the affected lung.
What causes contraction atelectasis?
Pulmonary or pleural fibrosis preventing full expansion.
Types causes of pulmonary edema
Haemodynamic (haemodynamic or cardiogenic) or increases in capillary permeability
Gross histology of haemodynamic pulmonary edema.
Basal regions of lower lobes affected first (dependent edema) due to higher hydrostatic pressure.
Microscopic histology of pulmonary edema.
Engorged alveolar capillaries.
Pale pink granular intra-alveolar transudate.
Haemosiderin laden macrophages may be present.
Pathology of microvascular alveolar injury
Inflammatory exudate leaks into interstitial space and sometimes the alveoli. When diffuse can lead to acute respiratory distress syndrome.
Production of inflammatory exudate in acute lung injury/ARDS.
Endothelial activation due to cytokines (local or systemic)
Adhesion and extravasation of neutrophils - release of proteases, ROS, cytokines.
Accumulation of intraalveolar fluid and formation of hyaline membranes. (damage to type II pneumocytes leads to surfactant abnormalities as well)
Epithelial necrosis impedes resolution of injury, but resolution can be achieved by macrophages.
Key histological features of ARDS
Heavy, firm, red, boggy lungs with diffuse alveolar damage. Alveolar walls lined with hyaline membranes.
Clinical features of acute lung injury
Profound dyspnea and tachypnea.
Increasing cyanosis and hypoxemia, resp filure and diffuse bilateral infiltrates.
V/Q perfusion mismatch.
What FEV1/FVC ratio suggests lung obstruction?
Less than 0.7
What FEV1/FVC ratio suggests restrictive disease?
Both are lowered, so ratio is normal.
What are the types of restrictive lung deficit?
Chest wall disorders
Chronic interstitial and infiltrative diseases
List some common obstructive lung diseases
Emphysema, chronic bronchitis, asthma and bronchiectasis.
What percentage of heavy smokers develop COPD?
35-50%
What is emphysema?
Irreversible enlargement of the airspaces distal to the terminal bronchiole, accompanied by destruction of their walls without obvious fibrosis. Small airway fibrosis is also involved.
Classifications of emphysema
Centriacinar, panacinar, paraseptal and irregular, but only the first two cause clinical obstruction.