Respiratory System and Defence mechanisms

Question 1

What is the anatomy of the Upper Respiratory Tract?

What is the anatomy of the Lower Respiratory Tract?

Answer 1

• Nasal cavity: has hairs and conchae
  Sinuses: air spaces in bone
  Larynx: affects pitch/volume
• Pleura: fluid-filled space between both layers to reduce friction and surface tension
  Trachea: ends at Carina (T4)
  Main bronchi: branch off into smaller bronchioles
  Alveoli: lined by a single epithelial layer consisting of Type I and II pneumocytes

Question 2

Define:
Compliance

Airway resistance

Tidal volume

Answer 2

• Lung’s ability to stretch/expand
• Resistance to airflow during respiration
• Volume of air breathed in/out at rest

Question 3

What controls ventilation?

Answer 3

Mechanoreceptors: prevent over-inflation of lungs

Chemoreceptors: central chemorec. in medulla oblongata, and peripheral chemoreceptors in carotid bodies. Respond to levels of O2, CO2, H+.

Question 4

What are the pulmonary defence structures?

How do you calculate alveolar ventilation?

Answer 4

• Nasal hairs, conchae, cilia, mucous, antimicrobials

= (Tidal volume - Residual volume) x frequency

Question 5

Relationship between the pleural membranes and lungs during respiration.

Difference in elastic recoil of chest and lung, and how it affects pressure?

Answer 5

• There are parietal (on chest wall), and visceral (on lungs) layers, and the cavity is sealed. Therefore, changes in thoracic volume = change in lung volume.
• Elastic recoil of chest wall is outwards, and that of the lungs is inwards. This ↓intrapleural pressure to be lower than atmospheric pressure.

Question 6

Explain the process of inspiration and expiration. Talk about pleural cavity and alveolar pressure.

Answer 6

Inspiration:
Respiratory muscles contract = ↑thoracic volume
↓Intrapleural pressure
Lungs expand to increase volume = ↓Palveoli
Palveoli < Patmosphere, air moves into alveoli

Expiration:
Respiratory muscles relax with elastic recoil = ↓thoracic volume
↑Intrapleural pressure
Lungs compressed to decrease volume = ↑Palveoli
Palveoli > Patmosphere, air moves out of alveoli

Question 7

Define and explain what occurs during a pneumothorax?

Define Hypoxia

Answer 7

• Pneumothorax - air in the pleural cavity, causing lung collapse; it can be an open/closed pneumothorax.

Intrapleural pressure is naturally < atmospheric due to the opposing recoil of chest and lungs. When one of the pleural layers rupture, air can enter the pleural space. Intrapleural pressure is then lost as the chest wall and lungs are no longer connected. They can now recoil in opposite directions, causing lung collapse (atelectasis).

• Hypoxia - lack of oxygen supply