Adaptations of the human lungs for gas exchange | Science

Starter quiz

Select the option which correctly finishes the sentence: Gas exchange is the process of…
- …air moving in and out of the lungs by inhaling and exhaling.
- …using sugar and oxygen to provide energy for life processes.
- …oxygen and carbon dioxide diffusing between the lungs and the blood. ✓
The diagram shows the human gas exchange system. Which letter on the diagram represents the bronchioles?
- A
- B ✓
- C
- D
- E
The diagram shows the human gas exchange system. Which letter on the diagram represents the alveoli?
- A
- B
- C ✓
- D
- E
A ______ is a group of cells working together to perform a specific function.
- 'tissue' ✓
In diffusion, the net movement of particles is...
- ...from areas of high concentration to low concentration. ✓
- ...from areas of low concentration to high concentration.
- ...between areas of equal concentration.
Which of the following are features of diffusion?
- The particles are randomly moving. ✓
- It requires energy from respiration.
- It is a passive process. ✓
- Once the particles are evenly spread they stop moving.

The diagram shows two structures in the lungs. What is the name of structure A in the diagram?
- 'alveolus' ✓
What type of blood vessel is labelled B?
- 'capillary' ✓
What level of organisation are alveoli?
- organ
- cell
- tissue ✓
- organ system
- molecule
There are many alveoli in the lungs in order to increase the ______ area of the lungs.
- 'surface' ✓
Select the option which correctly finishes the sentence: the walls of the alveoli are one cell thick in order to…
- create a short diffusion distance for oxygen and carbon dioxide to be exchanged. ✓
- increase the surface area of the lungs for gas exchange.
- maintain the concentration gradient between the alveoli and the capillary.
Match the adaptation to its property.
- One cell thick walls
  
  ⇔
  
  creates a short diffusion distance. ✓
- A large amount of alveoli
  
  ⇔
  
  provides a large surface area for diffusion. ✓
- Capillaries carry blood
  
  ⇔
  
  maintains a concentration gradient of gases. ✓

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The lungs are made up of tiny air sacs called alveoli.
Gas exchange takes place between air in alveoli and blood in capillaries.
There are millions of alveoli to increase the surface area of the lungs for gas exchange.
The walls of the alveoli are one cell thick to create a short diffusion distance for gas exchange.
The alveoli are surrounded by capillaries carrying blood, to maintain a concentration gradient for gas exchange.

Pupils often refer to the walls of the alveoli as "cell walls".

This lesson makes the scale of different parts of the gas exchange system clear (e.g. whether a structure is a tissue or cell).

Alveoli - Alveoli are tiny air sacs in the lungs that carry out gas exchange.
Capillary - A capillary is a narrow blood vessel that allows the exchange of substances between tissues and blood.
Diffusion - The movement of particles from a high concentration to a low concentration is known as diffusion.
Surface area - Surface area is the total area of all the exposed surfaces of an object.