Pathophysiology of COPD Flashcards
What is COPD a term for?
→ a mixture of chronic bronchitis and emphysema
How does lung function decline in healthy people vs people who smoke?
→ Lung function naturally declines with age
→ Lung function decline is accelerated in people who smoke
What can the harmful constituents of tobacco smoke cause?
→ Acute damage to respiratory tissue generating an inflammatory response
What happens with repeated exposure to tobacco smoke?
→ Inflammation becomes pathological
→ Creates chronic and irreversible dysfunction
What are the steps that cause inflammation in COPD?
→ Inhalation of reactive oxygen species and noxious chemicals
→ This causes tissue damage
→ The body responds by initiating an inflammatory response
→ Macrophages and neutrophils are activated
→ They secrete proteases to repair damaged tissue
→ Before damage can be repaired more inflammation occurs by smoking again
→ Increased protease burden which damages healthy tissues
What are the long term effects of inflammation?
→ Impaired mucociliary clearance
→ More vulnerable to respiratory infection
→ Generates more inflammation
→ Tissue remodelling
What is the layer of mucus in the airways for?
→ Trapping small particulates/ bacteria or viruses and moving them up the airways to remove them
What happens to the mucus with COPD?
→ Hypersecretion of mucus because toxic particles stimulate the production of it
→ They damage the way cilia work so they cannot beat as effectively
→ Mucus is not cleared well and bacteria live in the mucus and can infect lungs
What pathological features are present in the airways of someone with COPD?
→ Excess amounts of mucus within the airways
→ Weakened airway structure
→ Impairment of mucociliary clearance
→ Irritation of sensory neurons (coughing)
→ Decreased luminal area
What happens to alveoli in emphysema?
→ Decrease in surface area
→ Loss of elastin fibers means increased compliance and decrease in recoil
Why is not as much gas exchanged in emphysema?
→ Higher surface area to volume ratio
What consequence does emphysema have on breathing in and out?
→ Easier to expand the lungs (breathing in)
→ Harder to expel the air
→ Alveoli do not recoil so accessory muscles have to be used
What happens as a result of elastin degradation in COPD?
→ Loss of patency
→ Loss of elastic recoil
How can COPD lead to heart failure?
→ Chronic alveolar hypoxia → Hypoxic vasoconstriction → Pulmonary hypertension →Right ventricular hypertrophy → Heart failure
What are 3 conditions that can occur with COPD?
→ Hypoxaemia
→Hypercapnia
→ Acidaemia
