Respiratory Physiology Lecture 3 Part 15: Lung Compliance and Elastic Components

Question 1

Lung compliance is determined by?

Answer 1

• Elastic components of lungs and airway tissue (Elastin, collagen)
• Surface tension at the air-water interface within the alveoli

Question 2

Where are elastic components of the airways localized?

Answer 2

Localized in the alveolar walls, and around blood vessels and bronchi

Question 3

Lung elastic behaviour

Answer 3

Lung elastic behavior has less to do with simple elongation of fiber than it does with geometrical arrangements (Similar to Nylon stockings)

Question 4

What are the two elastic components?

Answer 4

• Elastin → hydrophobic protein
  Like a weak spring, low tensile strength, extensible → flexibilty
• Collagen
  Like a strong twine, high tensile strength, inextensible → resiliency

Question 5

What happens to the elastic components with aging?

Answer 5

With aging, elastin and collagen ↓ = lung compliance ↑ (Floppy lungs)

Question 6

What is the primary determinant of mechanical airway properties?

Answer 6

collagen

Question 7

Emphysema

Answer 7

Floppy lungs as a result of elastin destruction and alveolar wall destruction

• Increased compliance (Floppy lungs) with much less elastic recoil
• For little changes in P_TP there are large changes in lung volume

Question 8

Pulmonary Fibrosis

Answer 8

• Collagen deposition in alveolar walls (In response to lung injury, silica dust, asbestosis)
• Reduction in lung compliance (Stiff lungs)
  
  • Higher P_TP changes are necessary to generate changes in lung volume
  • Respiratory membrane is thicker making gas diffusion difficult so reduction in lung compliance

Question 9

low compliance = ?

Answer 9

stiff lungs

Question 10

high compliance = ?

Answer 10

floppy lungs