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At the nominal body temperature of 37 °C (99 °F), water has a vapour pressure of 6.3 kilopascals (47 mmHg); which is to say, at an ambient pressure of 6.3 kilopascals (47 mmHg), the boiling point of water is 37 °C (99 °F). A pressure of 6.3 kPa—the Armstrong limit—is about 1/16 of the standard sea-level atmospheric pressure of 101.3 ...
Pressure as a function of the height above the sea level. The human body can perform best at sea level, [7] where the atmospheric pressure is 101,325 Pa or 1013.25 millibars (or 1 atm, by definition). The concentration of oxygen (O 2) in sea-level air is 20.9%, so the partial pressure of O 2 (pO 2) is 21.136 kilopascals (158.
Atmospheric pressure, also known as air pressure or barometric pressure (after the barometer), is the pressure within the atmosphere of Earth. The standard atmosphere (symbol: atm) is a unit of pressure defined as 101,325 Pa (1,013.25 hPa ), which is equivalent to 1,013.25 millibars , [ 1 ] 760 mm Hg , 29.9212 inches Hg , or 14.696 psi . [ 2 ]
High-pressure nervous syndrome (HPNS) is a neurological and physiological diving disorder that results when a diver descends below about 500 feet (150 m) using a breathing gas containing helium. The effects experienced, and the severity of those effects, depend on the rate of descent, the depth and percentage of helium. [38]
Aerospace physiology is the study of the effects of high altitudes on the body, such as different pressures and levels of oxygen. At different altitudes the body may react in different ways, provoking more cardiac output, and producing more erythrocytes. These changes cause more energy waste in the body, causing muscle fatigue, but this varies ...
[28] [29] The lower viscosity of air at altitude allows air to flow more easily and this also helps compensate for any loss of pressure gradient. All of the above effects of low atmospheric pressure on breathing are normally accommodated by increasing the respiratory minute volume (the volume of air breathed in — or out — per minute), and ...
Dysbarism refers to medical conditions resulting from changes in ambient pressure. [1] Various activities are associated with pressure changes. Underwater diving is the most frequently cited example, but pressure changes also affect people who work in other pressurized environments (for example, caisson workers), and people who move between different altitudes.
Barotrauma is physical damage to body tissues caused by a difference in pressure between a gas space inside, or in contact with, the body and the surrounding gas or liquid. [1] [2] The initial damage is usually due to over-stretching the tissues in tension or shear, either directly by an expansion of the gas in the closed space or by pressure difference hydrostatically transmitted through the ...