L5 - Respiration I - Airflow

Question 1

What are the 3 types of airflow?

Answer 1

Laminar, Unstable, Turbulent.

Question 2

What is laminar flow?

Answer 2

The steady flow down a tube, fastest at the centre reducing at the edges.

Question 3

How is flow type determined?

Answer 3

By the Reynolds Number (Re).
- Re < 2000 = laminar Flow
- Re between 2000 and 3000 = flow is unstable switching between
laminar and turbulent.
- Re > 3000 = Turbulent

Question 4

When is the only time true laminar flow is present?

Answer 4

In the very terminal airways.

Question 5

What type of airflow is mostly present in lungs?

Answer 5

Turbulent

Question 6

Turbulent flow

Answer 6

• Under conditions of turbulent flow the rate of gas movement is proportional to the square root of pressure difference.
• A greater pressure gradient is needed to obtain the same flow under laminar conditions.

Question 7

What is Chronic Obstructive Pulmonary Disease (COPD)?

Answer 7

• A group of progressive obstructive lung diseases characterised by an increase in airway resistance and decrease in airflow.
  Which includes:
• Chronic Bronchitis - long standing inflammation of the bronchi and bronchioles.
• Emphysema - destruction of the alveolar walls.

Question 8

How is COPD managed?

Answer 8

Bronchodilators
Anticholinergics
B2 Adrenoreceptor agonists
Glucocorticosteroids

Question 9

What does Poiseuille’s Law state?

Answer 9

Airway resistance is proportional to gas viscosity and the length of the tube but it is inversely proportional to the 4th power of the radius.

Question 10

What factors are important to airway resistance?

Answer 10

Airway diameter - increased mucus secretion = increased resistance
- Oedema - fluid retention causes swelling and
narrowing of the airways = increased
resistance.