NAUI Diving Physics & Physiology

Question 1

What happens to air volume in the lungs as a diver ascends?

Accepted Answer

Air volume increases

Answer

As a diver ascends, the ambient water pressure decreases. According to Boyle's Law, as pressure decreases, the volume of a gas increases, assuming constant temperature. Therefore, the air in a diver's lungs will expand significantly as they rise towards the surface, necessitating continuous exhalation.

Question 2

Which gas law best explains the risk of lung overexpansion during ascent?

Accepted Answer

Boyle’s Law

Answer

Boyle's Law states that for a fixed amount of gas at constant temperature, pressure and volume are inversely proportional. As a diver ascends, the external pressure decreases, causing the air in their lungs to expand. If a diver holds their breath, this expansion can lead to severe lung over-expansion injuries.

Question 3

Why is nitrogen narcosis a concern for deep divers?

Accepted Answer

It impairs cognitive function

Answer

Nitrogen narcosis is caused by the increased partial pressure of nitrogen at depth, which acts as an anesthetic on the central nervous system. This impairment can lead to symptoms like confusion, poor judgment, euphoria, and reduced motor skills. For deep divers, these cognitive effects can significantly compromise safety and decision-making abilities.

Question 4

Which condition results from rapid ascent without proper decompression?

Accepted Answer

Decompression sickness

Answer

Decompression sickness (DCS), or 'the bends,' occurs when a diver ascends too quickly, causing dissolved nitrogen in the body's tissues to form bubbles. These bubbles can block blood flow, damage tissues, and cause a range of symptoms from joint pain to paralysis or even death. Proper ascent rates and decompression stops are crucial to prevent DCS.

Question 5

What physiological effect can occur when diving below 100 feet?

Accepted Answer

Greater risk of narcosis and toxicity

Answer

As divers go deeper, the partial pressures of gases in their breathing mixture increase. This elevated pressure increases the risk of nitrogen narcosis, which impairs judgment, and oxygen toxicity, which can lead to seizures. Both conditions become more pronounced and dangerous at depths below 100 feet, requiring careful gas management.

(NAUI) National Association of Underwater Instructors Certification Practice Test

(NAUI) National Association of Underwater Instructors Certification Practice Test

NAUI Diving Physics & Physiology