Lecture 4

Question 1

What is surfactant?

Answer 1

A detergent like fluid produced by type 2 alveolar cells

Question 2

Why does surface tension occur?

Answer 2

Because whenever there is an air-water interface there is an attraction between water molecules. The water molecules will be drawn towards each other creating a force that can collapse the alveoli

Question 3

What does surfactant do?

Answer 3

Reduces surface tension on the alveolar surface membrane so reduces tendency for alveoli collapsing.
Increases lung compliance
reduces lung’s tendency to recoil
Makes work of breathing easier

Question 4

Why is it easier to inflate a lung with saline than air?

Answer 4

Because there is no need to overcome surface tension (no air-water interface)

Question 5

Define compliance

Answer 5

Compliance is the change in volume relative to the change in pressure. It represents stretchability not elasticity as it doesn’t give any information on air getting out of the lungs.

Question 6

What does it mean if compliance is high?

Answer 6

There is a large increase in lung volume for a small decrease in pressure

Question 7

Where is the greatest compliance in the lung?

Answer 7

At the bottom of the lungs

Question 8

What is the difference between obstructive and restrictive lung disease?

Answer 8

Obstructive is when there is something obstructing air flow e.g Asthma and COPD
Restrictive is when lung expansion is restricted e.g Fibrosis and oedema

Question 9

What is spirometry?

Answer 9

A technique to measure lung function with measurements that can be classed as static or dynamic

Question 10

What are static measurements?

Answer 10

Measurements where the only consideration made is the volume exhaled

Question 11

What are dynamic measurements?

Answer 11

Measurements where the time taken to exhale a certain volume is what is being measured