Pathology: COPD Flashcards
Emphysema
- Emphysema is defined by what?
- What unit of the lung does emphysema affect
- Emphysema is defined by structural changes to the alveoli
- Affects the acinus (unit of lung from respiratory bronchiole –> alveolar sacs)
Emphysema
- Describe the pathophysiology
Lung tissue is exposed to irritants, eg. cigarette smoke.
1. Inflammatory reaction occurs in the alveoli
2. Immune cells are recruited.
3. Inflammatory mediators and proteases (elastase and collagenases) are released
4. Elastin and collagen are broken down –> reduced elasticity
Emphysema: consequences of loss of elastin for
- Inhalation?
- Exhalation?
- Alveolar wall integrity?
Inhalation: loss of elastin makes lungs less compliant –> airways easily expand
Exhalation: loss of elastin makes lungs collapse during exhalation –> air trapping distal to site of collapse
Alevolar wall integrity: loss of elastin leads to breakdown of thin alveolar walls –> neighbouring alveoli coalesce; reduced SA for gas exchange.
Emphysema
- How do patients compensate for airway collapse?
By pursed lip breahting - creates back pressure to help keep the airways patent
Emphysema
- 4 types: based on anatomic distribution within the acins?
Centricacinar (centrilobular) emphysema
Panacinar emphysema
Paraseptal emphysema
Irregular emphysema
Emphysema
- Which of these four is the most common?
Centriacinar emphysema
Centriacinar emphysema
- Where in the acinus is affected?
- Associated with which risk factor?
- Which lobes are typically affected?
- Does it cause clinically significant airflow obstruction?
Damages the central/proximal alveoli of the acinus
Cigarette smoking
Upper lobes
Yes
Panacinar emphysema
- Where in the acinus is affected?
- Associated with which risk factor?
- Which lobes are typically affected?
- Does it cause clinically significant airflow obstruction?
The entire acinus is uniformly affected
Alpha 1 antitrypsin deficiency
Lower lobes
Yes
Panacinar emphysema
- How does alpha 1 antitrypsin deficiency lead to panacinar emphsyema?
Acinar macrophages release proteases
Alpha 1 antitrypsin is a protease inhibitor - prevents protease overactivity and subsequent acinar damage
Deficiency –> too much acinar damage
Paraseptal emphysema
- Where in the acinus is affected?
- Where about in the lung does it typically effect?
- Complication?
- Does it cause clinically significant airflow obstruction?
- Distal alveoli of the acinar
Typically affects lung tissue on the periphery of the lung - Ballooned out alveoli on the lung surface can rupture –> pneumothorax
- No
Irregular emphysema
- Pattern?
- Is scarring involved?
- Does it cause clinically significant airflow obstruction?
Irregular
Yes
No
Emphysema
- 2 risk factors?
Smoking
Alpha 1 antitrypsin deficiency
Chronic bronchitis
- What is the definition?
- What unit of the lung does it affect?
Definition: a persistent cough with sputum production for >=3 months in >=2 consecutive years, in the absence of any other identifiable cause
Affects the bronchi and bronchioles
Chronic bronchitis
- 3 aspects of pathophysiology
Inflammation and fibrosis –> chronic airway obstruction
Hypertrophy + hyperplasia of bronchial mucinous glands (bronchi) and goblet cells (bronchioles) –> mucus plugging
Impaired cilia structure/function –> less mucociliary clearance
Chronic bronchitis
- Risk factors?
Tobacco smoking
Exposure to air pollutants, dust, silica
Family history
Complications
- Why does hypoxemia happen?
- Why do lung infections occur?
Mucus blocks air flow
Mucus plugging enables stasis of bacteria –> lung infection
