1. What does this… have to do with this? Diffusion Human Body

2. Respiratory system:  Our lungs work by diffusion!  Circulatory system transports oxygen and carbon dioxide

3. Examining your system.. Write your hypotheses....  How do you think physical activity will change your breathing rate and the amount of time you can hold your breath?

4. Who cares anyway?  What types of professions or people do you think would have a particular interest in understanding these body systems? Doctors Doctors Athletes Athletes Emergency responders Emergency responders Scuba Divers Scuba Divers

5. Scuba divers? What is going on here?!? That water sure is heavy!

6. What happens to the air in a scuba tank? 20 feet50 feet 80 feet ? ? ?

7. How does pressure change the way we breathe?   Scientific case study – Scuba Steve & friends....

8. Lab Investigation Depth  How does depth affect the diffusion of scuba tank “gas” into scuba divers “blood” Time  How does time under water change the amount of “gas” dissolved into a scuba divers “blood” 20 feet 80 feet 40 feet 20 min 40 min 60 min 60 feet

9. Results?? Depth of Diver  Gas dissolves into the blood faster as the diver goes deeper  The diver will accumulate more gas into his/her circulatory system on deeper dives Time under water  The volume of air dissolved in the blood stream increase with time under water  This gas can bubble out of solution if pressure is rapidly reduced

10. What is “the bends”?  Bends = decompression sickness (DCS)  DCS describes a condition arising from dissolved gasses coming out of solution and forming bubbles inside the body when pressure decreases.

11.  This happens when… Too much change (in pressure) too quickly Too much change (in pressure) too quickly  It is more likely to happen if... A diver spends a long time under water or does multiple dives A diver spends a long time under water or does multiple dives The diver goes very deep The diver goes very deep The diver rapidly returns to the surface from depth The diver rapidly returns to the surface from depth

12. Prevention and Treatment