What does this…What does this…

have to do with this?have to do with this?

DiffusionDiffusion

Human BodyHuman Body

Respiratory Respiratory system:system:

Our lungs work by Our lungs work by diffusion!diffusion!

Circulatory system Circulatory system transports oxygen transports oxygen and carbon dioxideand carbon dioxide

Examining your system..Examining your system..

Write your hypotheses....Write your hypotheses.... How do you think physical activity How do you think physical activity

will change your breathing rate will change your breathing rate and the amount of time you can and the amount of time you can hold your breath?hold your breath?

Who cares anyway?Who cares anyway? What types of What types of

professions or professions or people do you think people do you think would have a would have a particular interest in particular interest in understanding understanding these body these body systems?systems? DoctorsDoctors AthletesAthletes Emergency Emergency

responders responders Scuba DiversScuba Divers

Scuba divers? What is going on Scuba divers? What is going on here?!? here?!?

That water sure is heavy!That water sure is heavy!

What happens to the air in a scuba tank?What happens to the air in a scuba tank?

20 feet 50 feet 80 feet

??

?

How does pressure change the How does pressure change the way we breathe?way we breathe?

Scientific case study – Scuba Steve & friends....

Lab InvestigationLab InvestigationDepthDepth How does depth affect How does depth affect

the diffusion of scuba the diffusion of scuba tank “tank “gasgas” into scuba ” into scuba divers “divers “bloodblood””

TimeTime How does time under water How does time under water

change the amount of “change the amount of “gasgas” ” dissolved into a scuba divers dissolved into a scuba divers ““bloodblood””

20 feet

80 feet

40 feet20 min 40 min 60 min

60 feet

Results??Results??Depth of DiverDepth of Diver

Gas dissolves into the blood faster as Gas dissolves into the blood faster as the diver goes deeperthe diver goes deeper

The diver will accumulate more gas The diver will accumulate more gas into his/her circulatory system on into his/her circulatory system on deeper divesdeeper dives

Time under waterTime under water

The volume of air dissolved in the blood The volume of air dissolved in the blood stream increase with time under waterstream increase with time under water

This gas can bubble out of solution if This gas can bubble out of solution if pressure is rapidly reducedpressure is rapidly reduced

What is “the bends”?What is “the bends”? Bends = Bends =

decompression decompression sickness (DCS) sickness (DCS)

DCS describes a DCS describes a condition arising from condition arising from dissolved gasses dissolved gasses coming out of solution coming out of solution and forming bubbles and forming bubbles inside the body when inside the body when pressure decreases.pressure decreases.

This happens when…This happens when… Too much change (in pressure) too quicklyToo much change (in pressure) too quickly

It is more likely to happen if...It is more likely to happen if... A diver spends a long time under water or does A diver spends a long time under water or does

multiple divesmultiple dives The diver goes very deepThe diver goes very deep The diver rapidly returns to the surface from The diver rapidly returns to the surface from

depthdepth

Prevention and TreatmentPrevention and Treatment