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Flashcards in Deep Sea Deck (18):

Effect of depth on gases

Compression of gases to smaller and smaller volumes

Boyle's law


Boyle's law

The volume to wch a given qty of gas is inversely proportional to the pressure


Individual gases to whc a diver is exposed to

Carbon dioxide


Rapture of the depths

Nitrogen narcosis

Nitrogen @ high pressures

Effects similar to alcohol intoxication, gas anesthetics


Effects of nitrogen narcosis

120 ft - mild narcosis, diver experiences joviality and begins to lose his cares
150-200 ft - drowsiness
200-250 ft - strength wanes considerably; too clumsy to perform work required
Beyond 250- almost useless


MOA nitrogen narcosis

N dissolves in the fatty subs in the neuronal membranes
Physical effect on altering ionic conductance thru membranes
Reduces neuronal excitability


Extremely high tissue PO2 that occurs when oxygen is breathed at very high alveolar oxygen pressure

Acute oxygen poisoning


Symptoms encountered in acute oxygen poisoning

- breathing oxygen at 4 atmospheres pressure of oxygen (Po 2 = 3040 mm Hg) will cause brain seizures followed by coma in most people within 30 to 60 minutes
- nausea, muscle twitchings, dizziness, disturbances of vision, irritability, and disorientation


Oxygen free radicals

Forms of active oxygen

Superoxide free radical O2-
Peroxide radical - hydrogen peroxide


Effect of very high PO2 on blood oxygen transport

As the oxygen pressure rises, a large portion of the total oxygen is then dissolved in the water of the blood, in addition to that bound wt hgb


Effect of high alveolar PO2 on tissue PO2

Once the alveolar PO2 rises above a critical level, the hgb-oxygen buffer mechanism is no longer capable of keeping the tissue PO2 in the normal, safe range bet 20-60mmHg


Enzymes that rapidly remove free radicals

Peroxidases, catalases, superoxide dismutase


Effects of intracellular oxidation ( oxidizing free radicals)

- Oxidize the polyunsat FA that are essential components of many of the cell membranes
- oxidize some of the cellular enzymes, damaging severely the cellular metabolic systems

Nervous tissues are esp suscep bcos of their high lipid content (nervous system o2 toxicity) - most of the acute lethal effects of acute o2 toxicity are caused by brain dysfunction


Chronic oxygen poisoning

- Pulmonary disability
- after 12 hrs of 1atm o2 exposure: lung passageway congestion, pulmonary edema, atelectasis - damage to the linings of the bronchi and alveoli
- air spaces of the lungs are directly exposed to the high oxygen pressure


Decompression schedule

Diver in sea bottom for 60 mins at 190 feet

10min at 50 ft depth
17min at 40 ft depth
19min at 30 ft depth
50min at 20 ft depth
84min at 10 ft depth

Total time - 3 hrs


The type of scuba apparatus used in more than 99% of all sports and commercial diving

Open-circuit demand system
1. Tanks of compressed air/breathing mixtures
2. Reducing valve
3. Inhalation demand valve and exhalation valve
4. Mask & tube system wt small dead space


High-pressure oxygen (hyperbaric oxygen)

O2 usually administered at PO2S of 2-3 atm thru mask or endotracheal tube
Oxidizing free radicals - therapeutic benefits
- gas gangrene: clostridium (anaerobic)
- decompression sickness, arterial gas embolism, CO poisoning, osteomyelitis, MI


A condition wherein blood in the lungs is exposed to extremely high alveolar gas pressure