2.1.3 - The Mammalian Lung

Question 1

Describe The Role Of The Lungs?

Answer 1

~ Located in the thorax.

~ Maximises gas exchange while minimising the loss of water across the exchange surface.

Question 2

What Is The Pathway To The Lungs (Alveoli)?
(5 Points)

Answer 2

~ Nasal cavity / mouth.

~ Trachea.

~ Bronchi.

~ Bronchioles.

~ Alveoli.

Question 3

Describe The Trachea
(3 Points)

Answer 3

~ Contains c-shaped rings of cartilage, ensuring the tube remains open at all times and doesn’t collapse.

~ Has a layer of mucus covering the lining of the trachea, helps trap dust and pathogens preventing them from causing infection in the lungs.

~ Contains cilia, they waft mucus towards the top of the trachea removing any trapped particles and pathogens from the airways.

Question 4

What Is The Gas Exchange Surface In Mammals?

Answer 4

The alveolar epithelium in the lungs.

Question 5

Describe The Alveoli
(3 Points)

Answer 5

~ Alveolar wall consists of a single layer of epithelium, which is very thin and permeable for the easy diffusion of gases.

~ Surrounded by an extensive network of capillaries, where CO2 diffuses from capillaries -> alveoli. And oxygen diffuses from alveoli -> capillaries, to then be carried around the body.

~ A layer of moisture lining the alveoli, facilitating the diffusion of gases.

Question 6

Describe What Features The Mammalian Lung Has, Which Helps To Increase The Rate Of Gas Exchange
(4 Points)

Answer 6

~ Lots of alveoli, meaning there is a large SA for diffusion.

~ Alveolar epithelium and capillary epithelium are each one cell thick, giving a short diffusion pathway.

~ Have a good blood supply, creating a steep concentration gradient for CO2 and O2.

~ Ventilation, refresh the air in the alveoli, creating a steep concentration gradient.