Spearfishing Freediving Physiology for Spearfishing

Question 1

What physiological reflex helps divers conserve oxygen during a breath-hold dive?

Accepted Answer

The mammalian dive reflex, which slows heart rate and redirects blood to vital organs

Answer

The mammalian dive reflex triggers bradycardia (slowed heart rate) and peripheral vasoconstriction when the face contacts cold water, reducing oxygen consumption.

Question 2

What happens to air volume in a diver's lungs as they descend to greater depth?

Accepted Answer

Air volume compresses according to Boyle's Law, decreasing as pressure increases with depth

Answer

Boyle's Law states that gas volume decreases inversely with increasing pressure; at 33 feet (2 ATM), lung volume is halved compared to the surface.

Question 3

What is 'lung squeeze' and at what depths does it typically become a risk for spearfishers?

Accepted Answer

Pulmonary barotrauma from exceeding the lung's minimum compression volume, typically at depths greater than 100 feet for most divers

Answer

Lung squeeze occurs when depth compresses lung volume below residual volume, causing injury to lung tissue; it is a serious risk for divers attempting extreme depths.

Question 4

Why do experienced spearfishers pack-breathe (inhale in stages) before a dive?

Accepted Answer

To maximally load the lungs beyond tidal volume, increasing oxygen stores for the dive

Answer

Pack breathing staggers inhalation to exceed normal tidal volume, maximizing lung oxygen stores; it differs from hyperventilation as it does not flush CO2.

Question 5

What is the 'urge to breathe' physiologically driven by during a freedive?

Accepted Answer

Rising CO2 (carbon dioxide) concentration stimulating chemoreceptors in the brain

Answer

The primary drive to breathe is triggered by CO2 accumulation activating chemoreceptors in the medulla and carotid bodies, not by falling O2 levels.

Spearfishing Practice Test

Spearfishing Practice Test

Spearfishing Freediving Physiology for Spearfishing