Lungs

1
Lungs
By Jo Tansley and Nicola Collins
2
What are lungs?

• The lungs are organs that lie inside the ribcage.
• They are made up of alveoli, bronchi,
  bronchioles, and linked to the mouth by the
  trachea.

Please label the lung
3
(No Transcript)
4
What does it do?

• The lung is the essential respiration organ in
  air-breathing vertebrates.
• Its main function is to transport oxygen from the
  atmosphere into the bloodstream, and to excrete
  carbon dioxide from the bloodstream into the
  atmosphere.
• This exchange of gases is accomplished by alveoli.

5
Specialised features

• Cartilage rings of strong but bendy cartilage
  keeps the trachea open so air can pass through
  it.
• Goblet cells produce mucus to trap inhaled dust
  and other particles.
• Cilia hairs on the cells that line the trachea,
  bronchi and bronchioles. They waft mucus upwards
  away from the lungs.
• Elastic fibres between the alveoli. They
  stretch the lungs when we breath in and recoil
  when we breath out.

6
Alveoli

• The lungs contain about 300 million alveoli,
  representing a total surface area of 70-90 square
  metres, wrapped in capillaries.
• The alveoli have radii of about 0.1 mm and wall
  thicknesses of about 0.2 µm.
• Gas exchange is driven by passive diffusion and
  thus does not require energy for exchange.
• They diffuse oxygen into the blood stream, and
  carbon dioxide out of it.

7
How are alveoli adapted to speed up the process
of gas exchange?
Fill in the answers

• 1
• Very large surface area compared to volume
• 2
• Very thin walls (in some cases just on cell
  thick)
• 3
• Very good blood supply
• 4
• Steep concentration gradient between the alveoli
  and the blood vessels

8
The End