1. Gas exchange in Animals Internal 91155 (2.3)

2. Gas exchange in animals  All animals respire aerobically to release energy needed for cellular processes.

3. Gas exchange in animals  All animals respire aerobically to release energy needed for cellular processes.  Aerobic respiration needs oxygen and it releases carbon dioxide.

4. Gas exchange in animals  All animals respire aerobically to release energy needed for cellular processes.  Aerobic respiration needs oxygen and it releases carbon dioxide.  These two gases need to be exchanged across membranes: - Skin cells (in earthworms, some amphibians)

5. Gas exchange in animals  All animals respire aerobically to release energy needed for cellular processes.  Aerobic respiration needs oxygen and it releases carbon dioxide.  These two gases need to be exchanged across membranes: - Skin cells (in earthworms, some amphibians) - Through specialised organs – eg. Gills (fish) and lungs (reptiles, mammals, birds)

6. All gas exchange surfaces must be:  Moist – O 2 must dissolve before it can diffuse

7. All gas exchange surfaces must be:  Moist – O 2 must dissolve before it can diffuse  Thin – reduces the diffusion distance, making diffusion quicker

8. All gas exchange surfaces must be:  Moist – O 2 must dissolve before it can diffuse  Thin – reduces the diffusion distance, making diffusion quicker  Large in surface area – increases quantity of gases diffused per unit time.

9. Breathing  Animals need to breathe to facilitate gas exchange.

10. Breathing  Animals need to breathe to facilitate gas exchange.  Breathing is a physical process, involving muscular contractions to move air or water over the gas exchange surfaces (eg. Alveoli in the lungs)

11. Breathing  Animals need to breathe to facilitate gas exchange.  Breathing is a physical process, involving muscular contractions to move air or water over the gas exchange surfaces (eg. Alveoli in the lungs)  More rapid gas exchange allows for higher rate of respiration.

12. Breathing  Animals need to breathe to facilitate gas exchange.  Breathing is a physical process, involving muscular contractions to move air or water over the gas exchange surfaces (eg. Alveoli in the lungs)  More rapid gas exchange allows for higher rate of respiration.  This allows for increased metabolism and increased activity for the animal.

13. Transport of gases  This takes place through the circulatory system in most animals.

14. Transport of gases  This takes place through the circulatory system in most animals.  Therefore, gas exchange and transport systems are in close contact.