FREEDIVE!
by Terry Maas and David SipperlyGlossary
Apnea: Absence of breathing. Freedivers are apneic
throughout the duration of their dive.
Aperture: The iris or opening of a camera lens, which allows a fixed amount of light to
penetrate and expose the film in the camera. Each setting is assigned an f-stop number.
Arrythmia: An irregular heartbeat caused by various disturbances such as
drugs, breath-holding and forceful equalizations. Arrythmias are not uncommon. In certain
individuals they might prevent diving, depending upon professional medical evaluation.
Bluewater: Anywhere spearfishers hunt open-ocean gamefish species. It's
generally deep, blue and clear but sometimes may be shallow, green and even turbid.
Boyle's law: A law of physics that explains the pressure and volume
relationships of gases. It states that a volume of a gas is inversely proportional to the
absolute pressure, while the density of that volume of gas is directly proportional. This
principle explains how pressure affects air spaces within a diver's body and gear.
Bradycardia: The slowing of the heart beat. In divers,
it's.............................
Diving reflex: A rapid slowing of the heart seen
in all mammals just after the face is <d>immersed in cold water. This oxygen-saving
mechanism helps the freediver.......................
Hyperbaric oxygen treatments: Medical treatments
whereby oxygen is supplied under pressure in a recompression chamber to patients suffering
from the bends (decompression illness) and other medical conditions. May be of some use
for patients suffering brain injury after shallow-water blackout.............
Hypercapnia: Increased amount of carbon dioxide
in the blood. A diver who does not rest adequately between breath-hold dives will have
elevated carbon dioxide levels. This can predispose him to carbon dioxide toxicity or
blackout............
Immersion diuresis: A condition characterized by
the increased rate of urine output due to water pressure exerted on a diver’s body.
It is one cause of divers becoming chilled and dehydrated.
Laryngospasm: A protective reflex that causes closing of the vocal cords
to prevent passage of air or water into the lungs. This reflex occurs in unconscious
persons or those slightly anesthetized when an irritant such as water comes into contact
with sensitive tissue near the vocal cords.
Shallow-water blackout (SWB): An unconscious
state divers experience when the brain becomes deprived of oxygen. SWB <d>frequently
happens without warning, causing death by subsequent drowning..........
Sinus: A cavity found within the bones of the skull. The cavities are
interconnected to the nasal passages and are lined with a <d>mucus membrane and are
subjected to blockage resulting in a squeeze when a diver descends.
Squeeze: A pressure imbalance on an air space that is found within the
diver’s body or equipment. Such spaces include the ears, sinuses, mask, stomach and
wetsuit. The “squeeze” results from a pressure imbalance between these air
spaces and the water pressure surrounding the diver.
Spleen: An organ in the body containing red blood cells. Trained divers
experience a contraction of the spleen allowing extra red blood cells to enter the
circulatory system.
Static apnea blackout: Unconsciousness due to gradual oxygen depletion
caused by holding one’s breath too long. It can occur anywhere, particularly at the
surface, and is not associated with depth or pressure changes. It commonly occurs in
swimming pools.....................
.
prolong his dive.
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