Tissues in the gaseous exchange system 3.1.3

Question 1

What do the alveolar walls contain?

Answer 1

Elastic fibres that stretch during inspiration, but then recoil to help push air out during expiration.

Question 2

What are the trachea and bronchi supported by?

Answer 2

Rings of cartilage which prevent collapse, this is C shaped to allow flexibility.

Question 3

What are the bronchiole walls comprised of?

Answer 3

Smooth muscle and elastic fibres

Question 4

What is the role of mucus?

Answer 4

To trap dust, debris, and microorganisms, which is then transported to the back of the throat where it is either swallowed or coughed out.
If swallowed, the acid in the stomach kills pathogens

Question 5

What cell secretes mucus?

Answer 5

Goblet cell

Question 6

What is the role of smooth muscle and elastic tissue in the airway?

Answer 6

The smooth muscle can contract and constrict the airway, making the lumen of the airway narrower.
This may be important if there are harmful substances in the air.
Once the smooth muscle is contracted, it cannot reverse this effect on its own & requires the elastic fibres to elongate it again.
As the muscle relaxes the elastic fibres recoil to their original size - this acts to dilate the airway again