PADI Dive Physiology and Health 2 — Questions and Answers
Question 1: What condition occurs when nitrogen bubbles form in the tissues and bloodstream upon ascent?
- Oxygen toxicity
- Decompression sickness (Correct answer)
- Nitrogen narcosis
- Carbon dioxide toxicity
Correct answer: Decompression sickness
Decompression sickness (DCS) results from dissolved nitrogen coming out of solution and forming bubbles in the body when ascent is too rapid.
Question 2: Which organ is most sensitive to the neurological effects of decompression sickness?
- Heart
- Liver
- Spinal cord (Correct answer)
- Kidneys
Correct answer: Spinal cord
The spinal cord is particularly vulnerable to Type II (neurological) DCS, which can cause paralysis or sensory disturbances.
Question 3: A diver experiences joint pain and fatigue after surfacing. These are classic symptoms of which DCS type?
- Type III DCS
- Type I DCS (Correct answer)
- Type II DCS
- Pulmonary DCS
Correct answer: Type I DCS
Type I DCS involves musculoskeletal pain (the 'bends') and constitutional symptoms like fatigue, without neurological involvement.
Question 4: What is the primary first aid treatment for any suspected decompression sickness?
- Aspirin and rest
- 100% oxygen and evacuation to a recompression chamber (Correct answer)
- Rehydration fluids only
- Return to depth immediately
Correct answer: 100% oxygen and evacuation to a recompression chamber
Administering 100% oxygen and arranging transport to a hyperbaric chamber is the standard emergency response for DCS.
Question 5: Repetitive dives increase DCS risk because:
- Oxygen levels deplete over the day
- Residual nitrogen accumulates from previous dives (Correct answer)
- Narcosis effects compound with each dive
- Water temperature drops with each successive dive
Correct answer: Residual nitrogen accumulates from previous dives
Residual nitrogen from earlier dives adds to nitrogen absorbed on subsequent dives, increasing total tissue nitrogen load.
Question 6: Which factor does NOT increase a diver's risk of decompression sickness?
- Dehydration
- Heavy exercise post-dive
- Slow ascent rate (Correct answer)
- Obesity
Correct answer: Slow ascent rate
A slow ascent rate reduces DCS risk; it is a protective factor, not a risk factor.
Question 7: The recommended maximum ascent rate according to PADI guidelines is:
- 30 m/min
- 18 m/min
- 9 m/min (Correct answer)
- 5 m/min
Correct answer: 9 m/min
PADI recommends ascending no faster than 9 meters (30 feet) per minute to allow safe off-gassing.
PADI Dive Physiology and Health 2
What condition occurs when nitrogen bubbles form in the tissues and bloodstream upon ascent?