Exchange surfaces

Question 1

What are the 2 major parts of the gas exchange system in humans?

Answer 1

Conducting system - to bring oxygen to, and carbon dioxide away from the exchange surface.
Interface - exchange of gases between air and blood.

Question 2

What are the adaptations of the lungs?

Answer 2

1) Large surface area - more than 300 million alveoli (40-60m^2)
2) Thin exchange surface - alveoli walls are 1 cell thick (squamos epithelial). -Total distance gases to diffuse into blood <1um.
3) Diffusion gradient - good blood supply (extensive capillary network). -Ventilation.
4) Surfactant- made from lipid and protein. -Reduces the surface tension within each alveolus preventing collapsing.
5) Elastic tissue - Prevents alveoli bursting.-Recoils to return air sac to original size/shape after inhalation.-Recoiling helps expel air.

Question 3

What is the function and location of the cartilage tissue?

Answer 3

• Structural role.
• Found in trachea and bronchi.
• Prevents collapse during low pressure (inhalation).
• C-shaped in trachea to allow movement in neck and expansion of oesophagus.
• Plates in bronchus for support.

Question 4

What is the function and location of the smooth muscle tissue?

Answer 4

• Can contract to constrict the lumen, making it narrower.
• Involuntary action to vary air quantity to and from lungs.
• Occurs during an asthma attack.
• Found in trachea, bronchus and bronchioles.

Question 5

What is the function and location of goblet cells?

Answer 5

• Secretes mucus to trap dust and pathogens from air.

- Found in trachea and bronchus.

Question 6

What is the function and location of ciliated epithelium?

Answer 6

• Many tiny, hair like structures called cilia.
• Wafts mucus (containing particles) up the airway to back of throat, where then swallowed.
• Found in trachea, bronchus and bronchioles (not terminal ones).