A question about atmospheric pressure and scuba diving?
The pressure in the cabin of an aircraft is less than atmospheric pressure. Scuba divers are advised not to travel by air for at least 24 hours after a dive. Explain what they might experience if they ignore this advice.
Gas under higher pressure (under sea/lake) dissolves more readily in liquid (diver’s body). So the diver’s body could contain more dissolved gas than other peoples bodies.
When the pressure is suddenly lowered (aircraft cabin) the solubility of gas drops sharply and it separates from blood forming small bubbles in blood vessels. Blood turns fizzy. I expect it is not good. (http://en.wikipedia.org/wiki/Decompression_sickness)
Similar process is when you open carbonated water bottle (that is more intense of course) or simply ascend from deep water too quickly.
Gas under higher pressure (under sea/lake) dissolves more readily in liquid (diver’s body). So the diver’s body could contain more dissolved gas than other peoples bodies.
When the pressure is suddenly lowered (aircraft cabin) the solubility of gas drops sharply and it separates from blood forming small bubbles in blood vessels. Blood turns fizzy. I expect it is not good. (http://en.wikipedia.org/wiki/Decompression_sickness)
Similar process is when you open carbonated water bottle (that is more intense of course) or simply ascend from deep water too quickly.
References :
Without getting into complex use of partial pressures and concentrations; Use the analogy of a bottle of soda.
The soda is cabonated and under pressure while the lid is closed tight and the pressure inside the bottle is higher than the pressure outside the bottle. Unscrew the bottle cap and the pressure acting on the liquid reduces to atmospheric pressure and the soda emits bubbles of carbon di-oxide as the liquid can no longer hold the CO2 in solution. The higher the pressure the more gas can be dissolved in the liquid.
When diving at depth the air is delivered to the diver under pressure via an air regulator and demand valve. The deeper the diver goes the more volume he takes in of the air in each breath. Air contains approx 16% oxygen and 78% nitrogen plus CO2 and other inert gases. The deeper the diver goes and the longer he stays at depth the more gases dissolve into the bloodstream,(especially Nitrogen which has the highest concentration in air), and the body tissues through respiration. When the diver returns to the surface the pressure reduces. If the diver comes up slowly the gases are exhaled harmlessly in respiration as they have time to diffuse back into the bloodstream. But if a diver comes up too fast, the gases can form bubbles, just like in a soda bottle, only they appear in the tissues and blood stream. If they form in the blood vessels in/to the brain/heart etc then you can die or have a stroke or become paralysed as they block blood flow to the vital organs.
After a dive especially a deep one, say 100 feet, it takes 24 hours for all the nitrogen to diffuse out of the tissues and be expelled harmlessly. If you should hop on a plane the same day you dived and go to say 30,000 feet, atmospheric pressure is reduced and it could cause the Nitrogen dissolved in the bloodstream and tissues to come out of solution and cause bubbles. This is commonly termed as "the bends."
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