PADI Physics & Physiology of Diving Flashcards
6 cards from real PADI practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 PADI Physics & Physiology of Diving flashcards as text
What is the effect of cold water on a diver's nitrogen absorption rate compared to warm water?
Answer: Cold water slows absorption during the dive but may accelerate off-gassing risks on ascent due to vasoconstriction
Cold water causes vasoconstriction, which can reduce peripheral circulation and slow nitrogen absorption during the dive but may impair off-gassing on ascent, increasing DCS risk.
What percentage of the Earth's atmosphere is oxygen, and why is this percentage important to divers using standard scuba air?
Answer: 21% oxygen; standard air is safe at recreational depths but enriched oxygen (nitrox) changes the calculations
Atmospheric air is approximately 21% oxygen and 79% nitrogen; at recreational depths this mixture remains safe, but increasing partial pressure of oxygen must be monitored with nitrox mixes.
How does increased water pressure affect the density of breathing gas during a dive, and what is the practical implication?
Answer: Denser gas at depth requires more effort to breathe, increasing the risk of CO2 buildup
As depth increases, the gas a diver breathes becomes denser due to higher pressure, making it harder to inhale and exhale and increasing the risk of CO2 retention.
What is 'shallow water blackout' and what causes it in breath-hold divers?
Answer: Loss of consciousness near the surface caused by hypoxia after hyperventilating before a breath-hold dive
Shallow water blackout results from hyperventilating before a breath-hold dive, which lowers CO2 levels so the urge to breathe is suppressed until oxygen falls to unconscious levels near the surface.
What physiological change causes a diver to feel an increased urge to urinate during a dive (immersion diuresis)?
Answer: Hydrostatic pressure on the body causes blood to shift centrally, triggering the kidneys to increase urine output
The pressure of water compressing the body drives blood toward the core, which the body interprets as fluid overload, stimulating the kidneys to produce more urine.
Why is dehydration a significant risk factor for decompression sickness in scuba divers?
Answer: Dehydration reduces blood volume and circulation, impairing the transport and off-gassing of dissolved nitrogen
Adequate hydration supports efficient blood circulation, which is essential for transporting dissolved nitrogen to the lungs for off-gassing; dehydration impairs this process and raises DCS risk.