IDC Dive Physiology & Medical Considerations 3

Question 1

Henry's Law is most relevant to scuba diving because it explains:

Accepted Answer

How much gas dissolves in a liquid at a given pressure

Answer

How gas volume changes with pressure

Answer

The total pressure of a gas mixture

Answer

Why cold water holds less oxygen

Question 2

Pulmonary oxygen toxicity (the Lorrain Smith effect) differs from CNS oxygen toxicity in that it:

Accepted Answer

Occurs at lower partial pressures over longer exposures and affects the lungs

Answer

Causes convulsions more rapidly than CNS toxicity

Answer

Is not a concern at recreational diving depths

Answer

Only affects divers using closed-circuit rebreathers

Question 3

A patent foramen ovale (PFO) increases a diver's risk of DCS primarily because:

Accepted Answer

It allows venous nitrogen bubbles to bypass the lungs and enter arterial circulation

Answer

It reduces the diver's ability to equalize ear pressure

Answer

It causes rapid nitrogen absorption at depth

Answer

It increases susceptibility to nitrogen narcosis

Question 4

When a diver hyperventilates before a breath-hold dive, the primary danger is:

Accepted Answer

Lowering CO2 levels, delaying the urge to breathe until the diver loses consciousness underwater

Answer

Increased nitrogen narcosis

Answer

Oxygen toxicity from elevated O2 levels

Answer

Increasing nitrogen absorption

Question 5

Which cardiovascular condition presents the greatest immediate risk during strenuous scuba activities such as fighting a current?

Accepted Answer

Undiagnosed coronary artery disease with poor cardiac reserve

Answer

Mild hypertension controlled by medication

Answer

Previous knee surgery

Answer

Mild anemia

Question 6

During IDC training, student instructors learn that the safety stop at 5 meters (15 feet) for 3 minutes is recommended primarily to:

Accepted Answer

Allow additional off-gassing of dissolved nitrogen

Answer

Check buoyancy before full ascent

Answer

Equalize pressure in the ears one final time

Answer

Signal the dive boat of the diver's position

Question 7

An IDC instructor candidate should advise student divers that the primary sign of CO2 buildup (hypercapnia) during a dive is:

Accepted Answer

Headache and increased urge to breathe

Answer

Tingling in the extremities

Answer

Blue discoloration of the lips

Answer

Temporary vision disturbance