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How depressurization affect me?


Depressurization can arise as a result of a mechanical failure of the pressure controller , or if, in an unlikely event of a terrorist sabotage, ... an in- flight explosion.

Very simply, the effect of a rapid depressurization (more likely from an in-flight explosion) will cause your ears to 'pop' out. If you don't grab and don the oxygen mask immediately, you will, depending on the aircraft altitude, lose consciousness very rapidly as a result of hypoxia.

Please read on if you want to be very knowledgeable in this topic....

Physiology of Respiration

To understand the effect of hypoxia, you need to have a clear knowledge on the physiology of respiration.

The human body needs a constant supply of oxygen to break down food and produce energy. The body is unable to store oxygen and nervous tissue is very sensitive to deficiency of oxygen. The brain uses 20 percent of total resting oxygen consumption. Stopping its blood supply and subjecting it to anoxia (no oxygen) produces unconsciousness in as short as 10 seconds. Brain cell damage will occur after 4 minutes.

Carriage of Oxygen in the Body

Gases are exchanged between the body and the air in the lungs. The lungs are composed of numerous tiny blind ended sacs - the alveoli.

Oxygen passes from the alveolar air into the bloodstream and is carried by the red blood cells to the tissues. Carbon dioxide is carried from the tissues to the lungs where it is breathed out. This exchange of gases depends on a pressure gradient in the lungs and the blood stream.

Atmospheric pressure at sea level is 760 mm Hg or 14.7 psi (pounds per square inch). Air is a mixture of two main gases, oxygen (20%) and Nitrogen (80%). The pressure of each constituent in a mixture of gases is called its partial pressure. In a mixture of gases, the sum of the partial pressures is equal to the total pressure.

Each constituent in a mixture of gases, contributes to the total pressure in proportion to its volume contribution. Therefore, the partial pressure of oxygen in dry air is 160 mm Hg (20% of 760 mm Hg). A partial pressure of 160 mm Hg is more than adequate for normal body requirements.

The volume of the lungs is large compared with the amount of air taken in with each breath so that air exchange at each breath does not nearly empty and fill the lungs. Since oxygen is constantly being removed from the gas mixture in the alveoli and the carbon dioxide added to it through the alveolar walls, it follows that the composition of the alveolar air is different from that of the atmospheric air.

The composition of dry air at sea level is approximately:

Oxygen 14.5 %

Nitrogen 80.0 %

Carbon dioxide 5.5 %

Before working out the partial pressure of the constituents of the alveolar gas mixture, a further factor must be taken into consideration. Alveolar air is always completely saturated with water vapor at body temperature and this vapor exerts its own partial pressure.

Since the partial pressure of oxygen and carbon dioxide in the blood on the other side of the alveolar wall are different, there is rapid diffusion of these gases across the wall, so that almost instantaneous equilibrium is reached and the blood leaving the alveoli has the same partial pressures of oxygen and carbon dioxide as the alveolar air.

If the pressure of the oxygen in the lungs decreases, that is when rapid depressurization occurs, less oxygen will diffuse across the alveoli into the blood stream and less oxygen will reach the tissue. If cabin altitude is increased to 47,000 feet, even breathing 100 % oxygen, oxygen will diffuse out of the blood stream into the lungs and unconsciousness will be lost within 10 to 20 seconds.

Is this information sufficient for your knowledge?    


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