J Paul Martin MD Asheville NC On the Surface Divers float for two to five minutes bringing their heart rates down while simultaneously gulping air lung packing Their chest cavities visibly expand and increase functional lung capacity by 50 ID: 577079
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Slide1
Free Diving
J. Paul Martin, MDAsheville, NCSlide2
On the Surface
Divers float for two to five minutes, bringing their heart rates down while simultaneously gulping air “lung packing”. Their chest cavities visibly expand and increase functional lung capacity by 50%.Slide3
One Foot
Simply putting your face underwater initiates a “mammalian reflex”: Divers’ heart rates slow 10 – 25 percent. Capillaries in the arms, fingers, legs, and toes constrict to conserve oxygen and keep blood around vital organs.Slide4
33 Feet
Pressure builds one atmosphere (14.7 pounds per square inch) every 33 feet of sea water.Equalization of sinus and
eustachian
pressure must occur every few feet, calling up air stored in the lungs.Slide5
60 feet
Pressure compresses lungs to the point that divers’ bodies are now heavier than water. They enter a free fall. Pressure equalization becomes more difficult due to dwindling air supply.Slide6
100-200 feet
Lungs shrink to size of oranges. Another mammalian reflex begins: Blood shift. Blood plasma shifts into the lung capillaries creating volume
that is incompressible – therefore preventing total collapse of the lungs.
Oxygen continues to be consumed and CO2 levels increase – both can cause blackout on surfacing.Slide7