When things go wrong with the Respiratory System - Lecture 21 Flashcards
What are the types of respiratory diseases?
○ Obstructive: conditions which impede the rate of flow into and out of the lungs
○ Restrictive: conditions which cause reduced lung volume
○ Infection and inflammation
What is COPD?
○ Chronic obstructive pulmonary diseases
○ Narrowing of airways -> increased airway resistance
○ Increased air volume -> appearance of chest over-inflation
What are the main diseases of COPD?
○ Chronic bronchitis - narrowing
○ Emphysema - loss of elastic recoil
What is chronic bronchitis and the the two types?
○ Inflammation of the bronchi - mucus hypersecretion
○ Acute bronchitis
○ Chronic bronchitis
What is acute bronchitis?
○ Short-lived
○ Due to bacteria/virus
○ Lasts days/weeks
What is chronic bronchitis?
○ Due to smoking or environmental irritants
○ Lasts at least 3 consecutive months in 2 consecutive years
What are the symptons of chronic bronchitis?
○ Irritants cause inflammation in bronchi
○ Abnormal mucus secretion
○ Plugs airways
○ Prone to infection due to humid environment
○ Further inflammation
What is the treatment for chronic bronchitis?
○ Stop smoking
○ Bronchodilators
○ Antibiotics
What is are the causes of emphysema?
○ Smoking
○ Genetic α1 antitrypsin deficiency
What is the mechanism of emphysema?
○ Neutrophils & macrophages release elastase (normally inactivated by α1 antitrypsin)
○ Elastase destroys alveolar walls
What are the symptons of emphysema?
○ Shortness of breath of exertion
○ Hyperventilation
○ Expanded chest
What are the treatments for emphysema?
○ Enzyme supplements in α1 antitrypsin deficiency
○ Stop smoking
○ Lung transplant
However loss of alveoli is permanent and irreversible
What factors can cause asthma?
○ Hypersensitivity reaction to allergens
○ Air pollution
○ Exercise and cold air
○ Emotional stress
○ Genetics (?)
What are the symptoms of asthma?
○ Bronchoconstriction
○ Oedema of airway mucosa
○ Mucus secretion
What is the mechanism for asthma?
○ Mast cell activation -> Histamine and cytokine release -> Oedema, mucus, smooth muscle contraction (bronchoconstriction)
What are the treatments for asthma?
○ Bronchodilators e.g. Salbutamol (β2 adrenoreceptor agonist)
○ Anti-inflammatories - dampens mast cell activation
What causes restrictive lung disease?
Intrinsic or extrinsic to the lung parenchyma
What are the causes of intrinsic restrictive lung disease?
○ Long term exposure to dust: pneumoconiosis (asbestosis)
○ Drugs e.g. methotrexate
○ Rheumatoid arthritis
○ ARDS, IRDS
What are the causes of extrinsic restrictive lung disease?
Non muscular disease of the upper thorax
What is fibrosis?
○ Alveoli replaced by fibrotic tissue
○ Decreased lung compliance
○ Irreversible decrease in oxygen diffustion capacity
What are the causes of fibrosis?
○ Inhaled environmental and occupational pollutants
○ Cigarette smoke
○ Autoimmune disease
What are the two types of respiratory tract infections?
○ Upper: common but minor
○ Lower: Less common but serious
What is pneumonia?
○ Caused by bacteria
○ Affects bronchi & alveoli
○ Inflammatory exudate fills alveoli
○ Leads to ‘consolidation’
○ Lung tissue becomes firm and airless
What is the difference between bronchopneumonia and lobar pneumonia?
○ Bronchopneumonia: spread out
○ Lobar pneumonia: within a particular region
What is tuberculosis?
○ Caused by inhalation of mycobacterium tuberculosis
○ Latent - asymptomatic, non-infectious, granuloma in lung tissue
○ Active - spreads to bronchioles and circulation
What is the mechanism if tuberculosis?
○ Bacteria replicate in alveolar macrophage
○ Ineffective immune response
○ Bacteria move to lymph nodes
○ Collagen deposited around bacteria: breaks down structure of lungs
○ Lymph node erodes which cause bacteria to release and destruction of alveoli
How did Covid-19 work?
○ Binding of receptor expressed by host cells (lung epithelial cells)
○ Receptor = angiotensin-converting enzyme 2 receptor (abundant in type 2 alveolar cells)
