1. The Respiratory System
GCSE

2. Learning Outcomes By the end of today’s lesson you should:
Be aware of what respiration is and its components
Be aware of the process involved when we inhale (breathe in) and exhale (breathe out).
Know the difference between aerobic and anaerobic respiration
Be familiar with the term “Gaseous Exchange.”

3. What is Respiration?
Respiration is the process in which glucose is converted into energy useable for life processes.
Respiration involves the important component of breathing but be careful not to confuse respiration as just solely breathing.
There are 2 types of respiration that our bodies use for different activities...

4. Aerobic Respiration

5. Anaerobic Respiration

6. What is the difference between Aerobic and Anaerobic Respiration?
Q. Aerobic respiration occurs in the presence of...
A. Oxygen
Example of an Aerobic activity – Marathon Running
Q. Anaerobic respiration occurs in the ABSENCE of...
Example of Anaerobic activity – 100m Sprint

7. Aerobic Respiration
Aerobic respiration occurs in the presence of oxygen and is summarised by the following equation:
Glucose + Oxygen  Energy + Carbon Dioxide +Water
This type of respiration is used when the body continues an activity for a prolonged period of time.
The energy that is needed to allow this prolonged activity is produced using oxygen.

8. Aerobic Respiration Cont
In order for the aerobic system to function effectively, there has to be a constant supply of oxygen to the body and the working muscles.
For any activity that takes place over a long period of time (e.g. Marathon) it is important to have this constant supply of oxygen to the body otherwise the body would be unable to carry out the event.

9. Anaerobic Respiration
On the other hand, anaerobic respiration is the process where energy is made in the absence of oxygen.
The equation for anaerobic respiration is:
Glucose  Energy + Lactic Acid

10. Anaerobic Respiration Cont.
This type of respiration occurs when the body works without sufficient oxygen being delivered to the muscles.
Without the presence of oxygen, a waste product called lactic acid is produced in the muscles.
High lactic acid concentrations cause muscles to feel painful and can lead to cramp.
As oxygen is not being used to generate energy in anaerobic respiration, it can only be used for short bursts e.g. 100m sprint

11. Aerobic or Anaerobic?

12. Aerobic or Anaerobic?

13. Aerobic or Anaerobic?

14. Aerobic or Anaerobic?

15. Aerobic or Anaerobic?

16. Aerobic or Anaerobic?

17. Oxygen Debt
When our bodies respire anaerobically during vigorous exercise, supplies of oxygen are reduced to working muscles.
As there is an absence of oxygen, the body can only respire anaerobically for a maximum of 60 seconds.
During an anaerobic event such as the 100m sprint or a 50m freestyle event in swimming, our bodies will effectively ‘borrow’ oxygen and it will need to ‘paid back’ in order to break down the waste products produced (lactic acid).

18. Oxygen Debt
For example, Usain Bolt runs the 100m race in under 10 seconds and after the race finishes, he must continue to breathe deeply and heavily in order to replenish the oxygen or pay the oxygen debt.
One of the main reasons for completing a cool down after vigorous exercise is to enable the oxygen debt to be repaid and will allow any lactic acid to disperse which will avoid further discomfort.

19. The Recovery Period
Following intense exercise we have to take in extra oxygen which will help convert the lactic acid into simple waste products that have to be removed from the body.
Expiration of breath – removes the carbon dioxide and other waste products from our lungs.
Perspiration – is a form of temperature control and also removes excess water such as sweat at the same time that it is letting heat escape through evaporation from the skin. Although this heat is not really a waste product it must be released to prevent our bodies from overheating.
Excretion through urine and faeces – removes excess water and the other waste products from the lactic acid.

20. Breathing
This is a diagram of all the components involved in the breathing process

21. Inhalation (breathing in)
During inhalation:
The chest cavity changes shape and size.
The intercostal muscles contract which causes the rib cage to expand and pushes out the sternum (chest/breastbone)
The diaphragm will contract and will change shape from a concave or dome shape to a flattened shape.
The pressure inside the chest cavity will be reduced and therefore allows air to be sucked into the lungs.
The air we breathe in is high in oxygen and nitrogen but low in carbon dioxide.

22. Diagram of Inhalation

23. Exhalation (breathing out)
During exhalation:
The process is virtually reversed
The chest cavity changes in shape and size
The intercostal muscles relax, allowing the rib cage to drop downwards and inwards.
The diapgrahm relaxes and regains its concave or domed shape and this decreases the volume of the chest.
The pressure inside the chest will subsequently increase and force air out. The air exhaled is high in nitrogen and carbon dioxide.

24. Diagram of Exhalation

25. Gaseous Exchange
Gaseous exchange is the process where carbon dioxide is exchanged in the lungs for oxygen by diffusion.
The carbon dioxide produced as a waste product of respiration must be exhaled from the body and more oxygen is needed through inhalation.
Gaseous exchange takes place in the alveoli in the lungs.

26. Gaseous Exchange Cont.
The diagram shows gaseous exchange occurring at the alveoli in the lungs. The oxygen is taken into the blood and carried to the heart to be pumped around the body and the carbon dioxide is exhaled as a waste product of respiration.

27. Test

28. True or False?
Anaerobic exercise involves using oxygen to produce energy.
A triathlon competitor will use aerobic respiration.
Carbon dioxide is a waste product which causes discomfort and pain in the muscles.
Anaerobic respiration will be used in activities which can last up to 1 minute.

29. Questions??? What is the Oxygen Debt?
Give 3 examples of aerobic activities
Give 3 examples of anaerobic activities
Give 2 example of a sport that will use both aerobic and anaerobic respiration.
What are the 2 main muscles/group of muscles involved in breathing and changing the shape and size of the chest.