Scuba Diving Physics and Physiology of Diving 2 — Questions and Answers
Question 1: Which physiological condition is caused by breathing too little — allowing CO2 to build up in the body?
- Hypercapnia (Correct answer)
- Hypoxia
- Hyperoxia
- Hyperthermia
Correct answer: Hypercapnia
Hypercapnia is an excess of carbon dioxide in the blood, often caused by skip breathing or inadequate ventilation, and can cause headaches, confusion, and loss of consciousness.
Question 2: Why is hyperventilating before a breath-hold dive particularly dangerous?
- It lowers CO2 without raising O2, masking the urge to breathe until hypoxic blackout (Correct answer)
- It causes nitrogen to dissolve faster into the blood
- It increases buoyancy making descent difficult
- It raises heart rate to dangerous levels
Correct answer: It lowers CO2 without raising O2, masking the urge to breathe until hypoxic blackout
Hyperventilation purges CO2 so the diver feels no urge to breathe, but O2 can deplete to unconscious levels before the CO2 trigger kicks in, causing shallow water blackout.
Question 3: Dalton's Law of partial pressures states that the total pressure of a gas mixture equals:
- The sum of the partial pressures of each individual gas (Correct answer)
- The product of all individual gas pressures
- The pressure of the most abundant gas only
- The average pressure of all gases divided by depth
Correct answer: The sum of the partial pressures of each individual gas
Dalton's Law states that total pressure is the sum of each gas's partial pressure, which is critical for calculating safe O2 and N2 exposures in mixed breathing gases.
Question 4: What is barotrauma in the context of scuba diving?
- Tissue damage caused by a failure to equalize pressure differences across body air spaces (Correct answer)
- Skin burns from prolonged wetsuit pressure
- Muscle cramps from cold water exposure
- Vision loss from nitrogen narcosis at depth
Correct answer: Tissue damage caused by a failure to equalize pressure differences across body air spaces
Barotrauma occurs when a diver fails to equalize pressure in air spaces such as the ears or sinuses, causing pain, hemorrhage, or rupture of delicate tissues.
Question 5: How does water temperature affect a scuba diver's air consumption rate?
- Cold water increases air consumption because the body works harder to stay warm (Correct answer)
- Cold water decreases air consumption by slowing metabolism
- Water temperature has no measurable effect on air consumption
- Warm water increases air consumption due to faster breathing
Correct answer: Cold water increases air consumption because the body works harder to stay warm
Cold water causes the body to expend more energy maintaining core temperature, increasing the metabolic demand and therefore breathing rate and air consumption.
Question 6: An arterial gas embolism (AGE) is most commonly caused by which diving action?
- Holding the breath while ascending (Correct answer)
- Descending too quickly without equalizing
- Breathing nitrox at recreational depths
- Skipping the safety stop on a shallow dive
Correct answer: Holding the breath while ascending
AGE occurs when a diver holds their breath on ascent; expanding lung gas over-pressurizes alveoli, forcing bubbles into the pulmonary capillaries and arterial circulation.
Question 7: Buoyancy in water is governed by Archimedes' Principle. A diver achieves neutral buoyancy when:
- The weight of water displaced equals the total weight of the diver and equipment (Correct answer)
- The volume of water displaced exceeds the diver's body volume
- The diver's lung volume is at its maximum capacity
- The BCD is fully inflated
Correct answer: The weight of water displaced equals the total weight of the diver and equipment
Archimedes' Principle states an object is neutrally buoyant when it displaces water whose weight equals its own total weight, allowing the diver to hover effortlessly.
Scuba Diving Physics and Physiology of Diving 2
Which physiological condition is caused by breathing too little — allowing CO2 to build up in the body?