1.1 Intro

• What happens to pressure when humans descend beneath the sea?

  Pressure increases tremendously
• Why must air be supplied at high pressure to divers?

  To keep the lungs from collapsing
• What condition is caused by high alveolar gas pressure?

  Hyperbarism
• What can happen if high pressures exceed certain limits?

  They can cause major physiological alterations
• How deep is a column of seawater that exerts 2 atmospheres of pressure?

  33 feet (10.1 meters)
• What is the total pressure at 33 feet beneath the ocean surface?

  2 atmospheres
• What causes the second atmosphere of pressure at 33 feet?

  The weight of the water
• What is the pressure at 66 feet beneath the ocean surface?

  3 atmospheres
• What does Boyle's Law state about gas volume and pressure?

  Volume is inversely proportional to pressure
• What happens to the volume of gas at 33 feet where pressure is 2 atmospheres?

  It compresses to one-half liter
• At 233 feet, what is the volume of gas compressed to 8 atmospheres?

  One-eighth liter
• Why is Boyle's Law important in diving physiology?

  Increased pressure can collapse air chambers
• What is the actual volume of 1 liter at a depth of 300 feet compared to sea-level volume?

  It is equivalent to 10 liters at sea level
• What are the effects of sea depth on gas volume according to Boyle's Law?

  • Gas volume decreases with increased pressure
  • At 33 feet (2 atmospheres): 1 liter → 0.5 liters
  • At 233 feet (8 atmospheres): 1 liter → 0.125 liters
• What are the physiological effects of hyperbarism?

  • Major alterations in body physiology
  • Potentially lethal if pressure exceeds limits