Lecture 8: Respiratory diseases

Table to know

Step that fails	Physiology	Examples
Airways (obstructuve)	Increased resistance	Asthma fail, COPD, Cystic fibrosis
Lung/chest wall (restrictive)	Decreased compliance or weak pump	Pulmonary fibrosis, Obesity, neuromuscular disease
Diffusion	Increased thickness, decreased area	COPD, Pulmonary fibrosis, Pulmonary edema, Emphysema
Ventilation/Perfusion matching	Shunt and dead space	Pneumonia, pulmonary embolism
Transport	Decreased O2 content	Anemia, CO poisoning
Control	Decrease drive→ Hypoventilation	Opioid overdose, sleep apnea

Asthma

Bronchospasm

• Massive histamine release (mast cells)

• Smooth muscle contraction

Inflammation

• Thickening of airway wall

Mucus plug

• Hypersecretion further narrows lumen

COPD

Chronic bronchitis

• Airways produce excess mucus

• Cilia damaged

Emphysema

• Alveolar walls destroyed

• Elastic recoil lost

• Air trapped, hyperinflation

Pulmonary fibrosis

Loss of lung compliance

• Repeated injury

• Fibroblasts lay down collagen

• Loss of compliance

• Increased membrane thickness

Other respiratory diseases

Loss of lung compliance

Chest wall

Neuromuscular

Cardiogenic vs non

Cardiogenic

• Pressure

• Left heart failure= increased back pressure

• Fluid pushed into alveoli

Non

• Leak

• Sepsis, pneumonia, damage

• Surfactant lost