Worksheet B5d 1

The respiratory system

You are going to use models, charts, a short video and page 26 of the student book to learn about the respiratory system.

1Use the following words to label the diagram below.

air sacbronchiolebronchusdiaphragmintercostal muscles

lungpleural membranerib trachea

2List the parts of the respiratory system that:

a molecule of oxygen passes through before entering the blood, starting with the trachea

Trachea  ______

a molecule of carbon dioxide passes through after leaving the blood, starting with an air sac

Air sac  ______

Worksheet B5d 2

How we breathe in and out

The action of the diaphragm

Look at the bell jar with a rubber sheet. It is a model of our lungs, chest and diaphragm.

If you pull and push on the rubber sheet you can see how the lungs are filled and then emptied of air.

1If the rubber sheet is pushed downwards, this increases the volume inside the chest.

What happens to the balloons?

______

2If the rubber sheet is pushed upwards, this decreases the volume inside the chest.

What happens to the balloons?

______

Worksheet B5d 2 Continued

The action of the diaphragm and intercostal muscles

The diagram below shows inhalation and exhalation.

Complete the following sentences to explain how we breathe in.

3The intercostal muscles between the ______contract.

4This moves the ribs ______and ______.

5At the same time, the diaphragm muscle ______and moves ______.

6The volume of air inside the chest ______.

This decreases the pressure inside the chest. The air pressure outside the chest is higher so air enters the lungs.

Complete the following sentences to explain how we breathe out.

7The intercostal muscles ______.

8The ribs are moved ______and ______.

9At the same time, the diaphragm muscle ______and moves ______.

10The volume of air inside the chest ______.

This increases the pressure inside the chest. The air pressure outside the chest is now lower so air leaves the lungs.

Worksheet B5d 3

Breathing in and out

You will need:

  • two conical flasks
  • two bungs
  • rubber tubing
  • fresh limewater or bicarbonate indicator
  • new or sterilised mouthpieces

Method

1Pour equal amounts of fresh limewater or bicarbonate indicator into two conical flasks labelled
A and B.

2Join the flasks with rubber tubing.

3Gently breathe in and out through the clean mouthpiece.

4Repeat breathing in and out until there is a change in the content of one of the flasks.

Health and safety!

Take care – if you breathe in too deeply, you could suck up the limewater.

Conclusion

1Which flask are you breathing in (inhaling) through?

Flask ______

2Which flask are you breathing out (exhaling) through?

Flask ______

Worksheet B5d 3 Continued

3Explain what happened to the limewater/indicator in flask B.

______

4Explain what happened to the limewater/indicator in flask A.

______

5Which flask showed the presence of the most carbon dioxide?

______

6Where had this carbon dioxide come from?

______

7Which flask showed the presence of the least carbon dioxide?
(Air contains 0.04% carbon dioxide)

______

B5d 1

Technician’s notes

Class demonstration – Respiration by peas

Equipment:

  • germinating peas
  • dead, sterilised peas (sterilised by using a fungicide
    or alcohol, so they will not decay and produce heat)
  • vacuum flasks
  • clamps and clamp stands
  • cotton wool
  • thermometers

Support the flasks with clamp stands and clamp them upside down to prevent heat loss from neck. The germinating peas respire, releasing energy, some of which is ‘lost’ as heat.

Low demand activities

  • diagrams of fish gills or real fish gills
  • models and/or charts of respiratory organs
  • access to computers
  • access to Internet
  • short flash video from

Class demonstration – How we breathe in and out

Equipment:

  • bell jar
  • two balloons attached to a Y piece
  • rubber sheet firmly attached across the bottom of the bell jar

B5d 1 Continued

Class experiment – Breathing in and out

Equipment:

  • two conical flasks
  • two bungs
  • rubber tubing
  • supply of fresh limewater or bicarbonate indicator
  • new or sterilised mouthpieces

Health and safety!

New or sterilised mouthpieces must be used for each student. They can be sterilised in Milton for 30+ minutes.

Class demonstration – Lung capacities

Equipment:

  • graduated bell jar
  • two inverted mortars
  • sink
  • water
  • screw clip
  • new or sterilised mouthpieces

or

  • lung volume bag kit

Health and safety!

Check the students’ medical histories for conditions such as asthmabefore they take part in this demonstration.

New or sterilised mouthpieces must be used for each student. They can be sterilised in Milton for 30+ minutes.

Class demonstration – Exchange of air

You will need:

  • tank spirometer (this is expensive (£800) but it might be used for classes in the sixth form) orpocket spirometer (this is a simpler and cheaper version at £130)

Health and safety! Use of spirometers must be closely supervised by the teacher.

B5d 1

Answers

Worksheet B5d 1 – The respiratory system

1

Trachea

Lung

Intercostal muscles

Rib

Diaphragm

Pleural membrane

Bronchus

Bronchiole

Air sac

2

aTrachea  bronchus  bronchiole  air sac

Air sac  bronchiole  bronchus  trachea

Worksheet B5d 2 – How we breathe in and out

1Balloons inflate

2Balloons deflate

3Ribs

4Out, up

5Contracts, downwards

6Increases

7Relax

8Down, in

9Relaxes, up

10Decreases

Worksheet B5d 3 – Breathing in and out

1Flask A

2Flask B

3Turns milky; changes colour because of the presence of carbon dioxide

4Only slightly milky; faint change of colour or no changes

5Flask B

6From respiration in body cells such as muscles

7Flask A