Page 11 - 新思维科学学生用书8 样章

1 Respiration

1.2 Gas exchange

In this topic you will:
• find out how oxygen gets into your blood from the air, and

how carbon dioxide goes in the other direction
• do an experiment to help you to think about why the air
sacs in the lungs need to be very small

• do an experiment to compare how much carbon dioxide
there is in the air you breathe in and the air you breathe
out.

Getting started Key words

This topic is about two gases – oxygen and carbon dioxide. alveoli

Look at these diagrams. analogy

A B C capillaries
diffusion
expired air

gas exchange
haemoglobin

With your partner, answer these questions. inspired air
1 Which diagram shows the particles in a gas? limewater
2 Choose the correct phrases to complete these sentences:
In a gas, the particles are far apart / touching each other.

In a gas, the particles move freely / vibrate on the spot.

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