Here is question #2 for Aprils Scuba 101

answer 2 should read
increases the pressure gradient between the nitrogen pressure in the tissues and the alveolar pressure

Answer 3 should read
decreases the pressure gradient between the nitrogen pressue in the tissues and the alveolar pressure

Sorry, the poll answers did not fit.

Hope you enjoy these reviews.
;)

Mike

Breathing pure oxygen aids the individual with decompression sickness because it


! Increases the pressure gradient between the nitrogen pressure in the tissues and the alveolar pressure. Remember from physics that a pressure gradient is the difference in the pressure within a liquid and the gas in contact with that liquid. When this happens the gas within the liquid will attempt to equalize. A large pressure gradient is said to create a high driving force, meaning the gas exchange will take place rapidly. In decompression sickness the tissues of the body contain a high level of nitrogen. The alveolar air also has nitrogen within it, but less than what is within the tissues. As a result, there is a pressure gradient between the nitrogen in the tissues (high) and the nitrogen within the alveolar air (low). Hence, the nitrogen begins to come out. But, instead of air the diver breathes oxygen, there will be no – or very little – alveolar nitrogen. This will further increase the pressure gradient between the tissue nitrogen levels and the alveolar nitrogen levels. The result is a significant increase in the driving force of the tissue nitrogen, thus aiding in its elimination.