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The diagram shows the structure of a human lung - Junior Cycle Science - Question a - 2006
Question a
The diagram shows the structure of a human lung. Air passes in and out of the lungs, via the trachea, bronchi and bronchioles. Gaseous exchange takes place in the st... show full transcript
Worked Solution & Example Answer:The diagram shows the structure of a human lung - Junior Cycle Science - Question a - 2006
Step 1
Step 2
How does gaseous exchange take place in the structures labelled A?
Answer
Gaseous exchange in the alveoli occurs through a process called diffusion.
- Diffusion of Gases: As air enters the alveoli, oxygen (O₂) from the air diffuses into the blood in the surrounding capillaries, while carbon dioxide (CO₂) from the blood diffuses into the alveoli to be exhaled. This process relies on the concentration gradients of the gases.
- Capillary Exchange: The walls of the alveoli and capillaries are extremely thin, facilitating rapid and efficient gas exchange. The high concentration of O₂ in the alveoli compared to the blood allows oxygen to enter the blood easily, while the higher concentration of CO₂ in the blood compared to the alveoli drives carbon dioxide out of the blood.