It mainly deals with the change that occurs in the body on account of change in the physical conditions around the body.
Now, what the deep-sea physiology mainly concern about?
It means that the changes that occurs in the body, when it goes into depth in the sea.
Relationship of pressure to depth
The pressure increases as the depth increases, both of these are directly related to each other. It is shown in the table below as general consideration.
Gases-Boyle’s Law
The volume of gases decreases with the increase in the sea depth (the pressure) , both of these are indirectly related to each other.
Effect of partial pressure of individual gases on the body
Under this heading, we look at the dramatic changes that takes place in the body due to changes of the pressure of gases in the sea. The gases are
1. Nitrogen,
2. Oxygen; and
3. Carbon dioxide.
NITROGEN
About four-fifths of the air is nitrogen. At the sea-level ,nitrogen don’t cause any significant effects on the body, but some degrees of narcosis* occurs at the high pressures.
Just have this understand by simple values:
At 120 ft mood variations
At 150-200 ft drowsiness
At 200-250 ft too clumsy
Beyond 250 ft useless
* is a non-specific and reversible depression of function of Central Nervous System marked by insensibility produced by drugs.
Mechanism:
Of “Raptures of the Brain”
Nitrogen dissolves in the fatty substance in neuronal membrane, leads to the changes of conductivity in them. The ionic conductivity is affected by this action. As the ability of ions to pass changes, the neuronal excitability results.
OXYGEN
In simple words, we can say that as the body moves to depth of the sea. There is an increase partial pressure of oxygen in the sea that has two effects:
There is an increase in dissolved oxygen in water of blood and total oxygen content in the blood; whereas
There is no effect of oxygen dissolved in hemoglobin.
There are two effects of oxygen on the body depending upon the time of stay of the individual in that surroundings (depth and atmospheric pressure):
1. Acute O2 poisoning;
2. Chronic O2 poisoning.
Acute O2 poisoning
-Brain seizures followed by coma
(PO2: 4atm Time:30-40 min)
-nausea , muscle twitching , dizziness, irritability etc.
Mechanism:
Of Brain seizures
Acute form of O2 changes to free radicals that in turn into
-super oxide free radical and
-peroxide form.
At Normal level, above are formed and are removed by enzymes:
Peroxides, catalyses, super oxide dismutases,Hb-O2 buffer system.
Above normal level, the systems operating at normal level fails and leads to
Oxidation of polyunsaturated fatty acid and
Oxidation of cellular energy enzymes.
Both of above leads to Brain dysfunction by cell membrane damage and cell metabolism damage respectively.
NOTE to ponder over:
Brain cells are more affected than other cells as nerve membranes have more lipid portion than others and lipids are affected more by this.
Chronic O2 poisoning
Pulmonary disability results
(PO2: 1 atm Time: after 12 hours)
Mechanism:
Increase in oxygen pressure damages the bronchiole lining and alveoli leads to:
-Lung congenital
-Pulmonary edema
-Atelectasis
BUT, oxygen pressure to the other body tissues remains normal.
CARBON DIOXIDE
Its effect is CO2 toxicity that is due to below ones:
-Properly designed diving gear
-Rebreathing apparatus
Upto 80 mm Hg
Minute respiratory volume increase
Beyond 80 mm Hg
Depression of respiratory center leads to
-respiratory acidosis
-narcosis
-lethargy.
