Respiratory Physiology

Question 1

Breathing

Answer 1

process through which ventilation occurs

Question 2

Ventilation

Answer 2

movement of air in and out of lungs

Question 3

Respiration

Answer 3

exchange of gases between the environment and blood (external respiration) and between the blood and tissues (internal respiration)

Question 4

Out of what does the respiratory pump consist of?

Answer 4

• chest wall
• resp muscles
• neural control

Question 5

Ventilation - inspiration process

Answer 5

• Contraction of inspiratory muscles
• Enlargement of thorax (↑ volume)
• Decrease in pressure in relation to atmosphere
• Air flows into lungs

Question 6

Ventilation - expiration process

Answer 6

• Mostly passive, driven by lung elastic recoil
• Early expiration: some contraction of inspiratory muscles to help with braking of expiration
• Active/forced expiration: use of expiratory muscles

Question 7

How does elastic opposition work?

Answer 7

• Within the lung: networks of elastin and collagen fibres
• During inspiration these elastic forces need to be overcome
• The more stretched they are the greater the opposition to inflation

Question 8

How is surface tension reduced?

Answer 8

Surfactant:
- Phospholipid
- Produced by Type 2 Pneumocytes
- Reduces surface tension
- Changes surface tension according to lung volume
∴ reducing the work of breathing

Question 9

What is chest wall compliance?

Answer 9

• Also has an element of elasticity
• Chest wall has the tendency to expand, whereas the lungs want to recoil
• Balance of these two = resting volume of the lung (FRC – Functional residual capacity)

Question 10

What factors influence ventilation?

Answer 10

Lung volumes:
o End expiratory lung volumes
o Tidal volumes
Flow rates:
o Dependent on regional compliance and airway resistance
o Low flow rates – greater ventilation in the dependent lung regions
o High flow rates – greater ventilation in the non-dependent lung regions
Position:
o Physiological Position= Upright and Moving
Age
o Are children different?
o Traditionally – ventilation distribution in children is opposite to that of adults
* Greater ventilation in the non-dependent lung regions
o Reversal of pattern attributed to developmental differences in respiratory mechanics
Mode of ventilation
o Depends on the degree of spontaneous effort from the patient