1. KS3 Biology
8B Respiration

2. 8B Respiration Releasing energy The circulation system
Contents
8B Respiration
Releasing energy
The circulation system
The breathing system
Anaerobic respiration
Summary activities

3. How is digested food used by the body?
The body needs a constant supply of energy which comes from digested food.
Glucose from digested carbohydrate is an important substance that contains stored chemical energy .
When glucose reacts with oxygen a lot of energy is released.
In the body’s cells, glucose and oxygen react to release
energy . Some of this is released as heat and the rest is used by the cells.
The release of energy from glucose is called…
respiration

4. from the digestive system from the breathing system
What is respiration?
Respiration is the process that the body uses to release energy from digested food (glucose):
energy
glucose
oxygen
carbon
dioxide
water
from the digestive system
from the breathing system
useful!
waste product exhaled
This type of respiration is called aerobic respiration because energy is released with oxygen.
How do the glucose and oxygen needed for aerobic respiration get to the all the body’s cells?

5. Aerobic respiration: word equation activity

6. Comparing respiration and combustion
Burning is the reaction between a fuel and oxygen.
This reaction is called combustion:
fuel
oxygen
carbon
dioxide
water
When something burns, heat and light energy are
released and carbon dioxide and water are also produced, so combustion is similar to respiration.
However, combustion is different because it is not a controlled reaction. Respiration is a controlled reaction which slowly releases energy from food in the body’s cells and the cells do not catch fire!

7. 8B Respiration Releasing energy The circulation system
Contents
8B Respiration
Releasing energy
The circulation system
The breathing system
Anaerobic respiration
Summary activities

8. The body’s transport system
The dissolved food and oxygen needed for respiration are carried around the body by the circulation system.
The circulation system includes the blood, blood vessels, the heart and the lungs.
Which part of the circulation system actually carries dissolved food and oxygen to the body’s cells?
body’s
cells
lungs

9. Blood
The blood carries oxygen and dissolved food to all the body’s cells so that respiration can take place.

10. Your beating heart
The heart is made of very special muscle called cardiac muscle.
This is because it has to keep beating for the whole of a person’s life!
If you tried to do the same action repeatedly (like the heart does), your muscles would get tired and after a while stop working.
For example, if you keep clenching and unclenching your hand, it will get tired and may even start to get cramp.
Why is it important for respiration that the heart keeps beating?

11. Different types of activity
What happens to the pulse rate whilst someone is running?
The body needs to release more energy:
so oxygen and glucose need to reach
muscle cells quickly;
so blood is pumped around the body faster;
so the pulse is faster.
What happens to the pulse rate whilst someone is sleeping?
The body needs to release less energy:
so oxygen and glucose need to reach muscle cells slowly;
so blood is pumped around the body slower;
so the pulse is slower.

12. 8B Respiration Releasing energy The circulation system
Contents
8B Respiration
Releasing energy
The circulation system
The breathing system
Anaerobic respiration
Summary activities

13. What is breathing?
The breathing system is used by the body to get the oxygen needed for respiration.
It is also use to get rid of the waste product of respiration, the gas carbon dioxide.
Breathing in and breathing out are separate processes in the body:
Breathing in is also known as inhalation. When you inhale you breathe in air, including oxygen, into your lungs.
Breathing out is also known as exhalation. When you exhale you breathe out the contents of our lungs and getting rid of the waste gas carbon dioxide.

14. Inhalation

15. The alveoli
In the lungs, oxygen travels to thousands of tiny air sacs called alveoli. These are covered with tiny blood vessels.
The alveoli give the lungs a huge surface area which is equal
in size to the area of a tennis court!

16. Gas exchange
Gas exchange takes place in the alveoli – oxygen is transferred into the blood and carbon dioxide moves out of the blood.
Each alveolus has a thin wall so that gas exchange between
the lungs and the blood can take place quickly.

17. Exhalation

18. Comparing inhaled and exhaled air
What are the differences between inhaled and exhaled air?
inhaled air
nitrogen (78%)
oxygen (21%)
carbon dioxide (0.04%)
other
exhaled air
nitrogen (78%)
oxygen (17%)
carbon dioxide (4%)
other
How could you test for the differences between inhaled and exhaled air?

19. 8B Respiration Releasing energy The circulation system
Contents
8B Respiration
Releasing energy
The circulation system
The breathing system
Anaerobic respiration
Summary activities

20. Aerobic and anaerobic respiration
When the body is able to supply the cells with the oxygen and glucose that they need, it carries out aerobic respiration.
energy
glucose
oxygen
carbon
dioxide
water
Anaerobic respiration
When the body cannot supply the cells with the oxygen needed to break down glucose, then it has to carry out anaerobic respiration. Energy is released without oxygen:
energy
glucose
lactic
acid

21. Not enough oxygen! lactic acid energy glucose carbon dioxide lactic
When anaerobic respiration takes place, the lactic acid produced soaks the muscle cells and prevents muscles from doing their job. This causes fatigue and sometimes cramp.
After activity that has lead to anaerobic respiration, the person involved pants and breathes heavily.
This happens because they need lots of oxygen to get rid of lactic acid that has built up in their body.
carbon
dioxide
lactic
acid
oxygen
water

22. Anaerobic respiration: word equation activity

23. 8B Respiration Releasing energy The circulation system
Contents
8B Respiration
Releasing energy
The circulation system
The breathing system
Anaerobic respiration
Summary activities

24. Glossary
aerobic – The type of respiration that occurs with oxygen.
alveoli – Tiny air sacs in the lungs where gas exchange takes place.
anaerobic – The type of respiration that occurs without oxygen.
exhalation – The process of breathing out.
glucose – A type of sugar that the body releases energy from during respiration.
inhalation – The process of breathing in.
respiration – The process that the body uses to release energy from digested food.

25. Anagrams

26. Multiple-choice quiz