KIN 3304: Diving Physiology
23 Cards in this Set
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pressure
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-continuous physical force exerted on or against an object by something in contact with it.
- pressure=Force/Area
- Measured in atmospheres as pounds per sq inch.
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PSI of Air
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-Air only exerts 14.7 PSI
-At sea-level, we are exposed to about 14.7 psi of pressure. This means that each square inch of our bodies has the equivalent force of about 14.7 pounds pressing on it.
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Pressure of Water on the human body
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◦ Water is about 800x more dense than air.
◦ The pressure we feel exerted on our body in 10 miles of air is equaled by a mere 33 feet of sea water.
◦ For every 33 feet, we get 1 atm.
◦ Pressure is main factor when discussing diving.
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Decompression Illness
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◦ Results from a reduction in the ambient pressure surrounding a body.
◦ 3 types:
▪ DCS- Decompression Sickness
▪ AGE- Arterial Gas Embolism
▪ Lung Over-expansion Injuries
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Decompression Sickness
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◦ AKA Caisson disease, “the bends”
◦ 2.8 cases of Caisson disease per 10,000 dives.
▪ Males have a 2.6 times greater risk to get than females( usually because males are more stupid and try dumb things)
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What leads to decompression sickness or the bends?
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Most divers breathe air when they go underwater. This results in increased concentrations of nitrogen dissolved in the blood and tissues of the diver. If a diver spends sufficient time at depth, the blood and tissues will have elevated concentrations of dissolved nitrogen in them. These n…
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Why did some of the people who built the Brooklyn bridge develop Caisson's Disease even though they did not get wet?
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Builders who made Brooklyn Bridge would have to go down the caisson cylinder-like structures that were in the water. Although they weren't diving underwater, they still felt the pressure the water put on the caisson structures. Once they would come back up to the surface the pressure chan…
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Why "The Bends"?
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That's because nitrogen bubbles blocking circulation in the small veins of joints (elbows, knees, shoulders) cause pain that a diver may seek to relieve by bending those joints
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How is DCS treated?
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All cases of decompression sickness should be treated initially with 100% oxygen until hyperbaric oxygen therapy (100% oxygen delivered in a high-pressure chamber) can be provided
-This device works by gradually increasing and then decreasing air pressure around the body, which forces ga…
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Arterial gas embolism
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▪ An embolism is anything in blood stream that can block blood flow.
▪ AGE then is → a bubble on the arterial side., that can therefore, block blood flow to parts of the body such as the brain, and will eventually cause a stroke.
Causes: most often by the expansion of respiratory …
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Lung Over-expansion Injuries
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▪ Pneumothorax – rupture of a lung into the pleural cavity collapsing the lung either partially or completely.
▪ Mediastinal Emphysema – air is trapped in center of the chest pressing on the heart and major blood vessels.
• Subcutaneous Emphysema – when air migrates under the skin t…
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Patent Foreman Ovale (PFO)
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◦ relatively little effect on non-divers.
◦ Bubbles can be found in lungs after dives → normally trapped by lungs and filtered out.
◦ Bubbles in people with PFO bypass the lungs and can lead to complications such as DCS.
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Nitrogen Narcosis
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◦ pressures incurred while diving cause gases to dissolve into the blood allowing a high percentage to reach the nervous system.
◦ The higher amount causes a narcotic effect such as euphoria or anesthesia.
▪ ^^ kind of like laughing gas (N2O) that dentists use.
-Signs of nitr…
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Oxygen Toxicity
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◦ the air we breath is 78% Nitrogen, 20.93% Oxygen, 0.03% CO2, and 1% trace gases.
◦ Pure O2 can be lethal beyond 30 feet below sea level.
◦ Deeper depths and higher concentrations of O2 raise risk of oxygen toxicity.
◦ 2 types:
▪ Pulmonary
▪ Central…
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Pulmonary Oxygen toxicity
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▪ form of oxygen poisoning that directly affects the lungs
▪ rare in recreational diving, more of a concern with TECH diving
▪ Symptoms are that it begins with throat irritation, then goes to lungs, and in severe cases, causes a burning sensation in the chest → can lead to a decr…
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CNS Oxygen Toxicity
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▪ more serious → CNS toxicity doesn't have a useful PO2 and time relationship.
▪ Symptoms are visual disturbances, ear disturbances, nausea, twitching, irritability, and dizziness.
▪ Most serious problems are hyperoxic seizures. This means that the victim has serious convulsions cau…
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How oxygen toxicity works
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When diving, the rising water pressure increases, according to Dalton's Law, the partial pressure of oxygen. Oxygen represents about 20% of air at sea level. However, while that percentage stays the same at depth, we inhale many more oxygen molecules. At the 130 feet dive limit for recrea…
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Hypocapnia
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◦ AKA shallow water blackout
◦ lack of CO2
◦ From either hyperventilation or unintentional (due to stress or fright).
▪ Example/ Swimming in a shallow part of a lake casually, all of a sudden, you brush against something, believing you accidentally brushed against a shark (…
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Shallow water blackout in more detail
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Hyperventilation artificially depletes CO2 causing hypocapnia. Hypocapnia reduces the reflexive respiratory drive, allows the delay of breathing and leaves the diver susceptible to loss of consciousness from hypoxia. Thus it is not the lack of oxygen that creates in us the urge to breathe…
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Hypercapnia
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-abnormally elevated CO2 levels in the blood
◦ usually result of over exertion, but can be from dead air spaces (in a mask or snorkel).
◦ Related to “skip” breathing →
▪ causes headaches, confusion, and a feeling of air starvation.
◦ Loss of consciousness is your body's w…
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Carbon Monoxide Poisoning
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◦ contaminated air can contain carbon monoxide
◦ hemoglobin binds with CO more readily than O2 (can take 8-12 hours to eliminate once in the respiratory system).
Increased pressure allows oxygen to continue bonding at depth, but as the diver ascends, and the pressure is reduced, O…
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High Pressure Nervous Syndrome
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◦ related to deep diving
◦ can happen as shallow as 300 feet but ore common beyond 400 feet.
◦ Symptoms are hand tremors, cramps, nausea, vertigo, and loss of coordination.
◦ No clear cause to why!!! BUT it does result from helium interfering with the peripheral nervous system…
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Exercise and Diving
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◦ Can be a positive or negative thing
◦ Exercise more than 12 hours before diving can have a protective effect
◦ Avoid rigorous exercise immediately (within a couple hours) before or after diving.
◦ Dehydration and Fatigue can be a precursor to dive related in…
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KIN 3304: Diving Physiology