1. The Respiratory System
KS4 Physical Education
The Respiratory System
Photo: © Sebastian Kaulitzki, shutterstock.com
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2. What we will learn in this presentation:
Learning objectives
What we will learn in this presentation:
The structures of the respiratory system and their functions
The mechanisms of breathing
How gases are exchanged during breathing
The composition of inhaled and exhaled air.
Teacher’s note: This presentation covers the following exam board specifications:
Edexcel – Topic 1.2.3: A healthy active lifestyle and your respiratory system
AQA – Section 3.1.1: The range of physical activities and the different roles that the active participant can choose from – The difference between aerobic and anaerobic exercise
OCR – Section 3: Informed decision making using the principles of training an safe exercise – Short term effects of an active healthy lifestyle, long term effects of an active healthy lifestyle, definitions and examples of aerobic and anaerobic exercise and training

3. The role of the respiratory system
The respiratory system helps the body obtain oxygen for respiration and remove the waste product carbon dioxide.
As we breathe, oxygen moves through the surface of the lungs into the body. It is then absorbed by the blood cells and transported around the body via the blood vessels.
The respiratory system is adapted for efficient exchange of gases between the lungs and the blood.
Photo: © Sebastian Kaulitzki, shutterstock.com

4. The respiratory system

5. Mechanisms of breathing – inspiration
When you breathe in:
Intercostal muscles pull ribs up and out
the intercostal muscles between the ribs contract, pulling the chest walls up and out.
the diaphragm muscle below the lungs contracts and flattens, increasing the size of the chest.
the lungs increase in size, so the pressure inside them falls. This causes air to rush in through the nose or mouth.
Diaphragm contracts and moves down

6. Mechanisms of breathing – inspiration

7. Mechanisms of breathing – expiration
When you breathe out:
the intercostal muscles between the ribs relax so that the chest walls move in and down.
the diaphragm muscle below the lungs relaxes and bulges up, reducing the size of the chest.
the lungs decrease in size, so the pressure inside increases and air is pushed up the trachea and out through the nose or mouth.
Ribs move in and down
Diaphragm relaxes and bulges up

8. Mechanisms of breathing – expiration

9. Gas exchange at the alveoli
The alveoli are bunches of tiny air sacks inside the lungs.
Each individual sack is called an alveolus.
When you breathe in, they fill with air.
The alveoli are covered in tiny capillaries (blood vessels).
Gases can pass through the thin walls of each alveolus and capillary, and into the bloodstream.
Gases can also pass from the bloodstream into the alveolus.

10. Gas exchange at the alveoli

11. Composition of inhaled and exhaled air
Gas
Amount in inhaled air
Amount in exhaled air
Oxygen
Carbon dioxide
Nitrogen
Water vapour
21%
Very small amount
79%
Small amount
17% 3%
79%
Large amount
What are the main differences between inhaled and exhaled air?
Teacher’s note:
Ask the students to compare the relative amounts. Point out that:
The amount of oxygen inhaled is greater than the amount of oxygen exhaled. Consider the efficiency of respiration at the cells.
The amount of carbon dioxide is greater in exhaled air.
The amount of nitrogen is the same.
Mouth to mouth resuscitation works because there is still a lot of oxygen left in exhaled air.
Why does mouth-to-mouth resuscitation work?

12. The nasal passages and lungs
Air is drawn into the body via the nose or mouth. There are advantages to breathing through your nose:
the air is warmed so that it is closer to body temperature
tiny hairs and mucus in the nose filter the air, preventing larger dust and pollen particles reaching the alveoli
mucus moistens the air, making it easier for the alveoli to absorb.
Teacher’s note:
Advantages: higher volume of air intake, countering oxygen debt (covered in next presentation); a second option to make breathing easier (e.g. if nose is blocked); exhalation through your mouth allows you to speak.
Photo: © 2009 Jupiterimages Corporation
What are the advantages of being able to breathe through your mouth as well?

13. The respiratory system

14. Summary

15. Exam-style questions
Describe the passage of oxygen from the nasal passages to the bloodstream.
This diagram shows a cross section of the respiratory system. a
a) Which structures aid movement during breathing?
b) Name the structures labelled a, b, c and d.
From the nasal passages, the oxygen in the air passes the larynx, down the trachea, into the bronchi. It then passes through the bronchioles and into the alveoli. Oxygen passes through the semi-permeable walls of the alveoli, into the capillaries which cover the alveoli walls.
2. a) diaphragm and intercostal muscles.
b) a – bronchi, b - lungs, c – alveoli, d – diaphragm b d C

16. Can you remember all these keywords?
Larynx
Trachea
Bronchus / Bronchi
Bronchioles
Alveoli
Diaphragm
Intercostal muscles