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Time Of Useful Consciousness
Time of useful consciousness (TUC), also effective performance time (EPT), is defined as the amount of time an individual is able to function effectively (e.g. perform flying duties) in an environment of inadequate oxygen supply. It is the period of time from the interruption of the oxygen supply or exposure to an oxygen-poor environment to the time when useful function is lost, and the individual is no longer capable of taking proper corrective and protective action. It is not the time to total unconsciousness. At the higher altitudes, the TUC becomes very short; considering this danger, the emphasis is on prevention rather than cure. For orbital altitudes and above, that is, direct exposure to space, 6–9 seconds of consciousness is expected. Medical analysis and variations There are many individual variations of hypoxia, even within the same person. Generally, old age tends to reduce the efficiency of the pulmonary system, and can cause the onset of hypoxia symptoms sooner ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aviation
Aviation includes the activities surrounding mechanical flight and the aircraft industry. ''Aircraft'' includes fixed-wing and rotary-wing types, morphable wings, wing-less lifting bodies, as well as lighter-than-air craft such as hot air balloons and airships. Aviation began in the 18th century with the development of the hot air balloon, an apparatus capable of atmospheric displacement through buoyancy. Some of the most significant advancements in aviation technology came with the controlled gliding flying of Otto Lilienthal in 1896; then a large step in significance came with the construction of the first powered airplane by the Wright brothers in the early 1900s. Since that time, aviation has been technologically revolutionized by the introduction of the jet which permitted a major form of transport throughout the world. Etymology The word ''aviation'' was coined by the French writer and former naval officer Gabriel La Landelle in 1863. He derived the term from the v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Excess Post-exercise Oxygen Consumption
Excess post-exercise oxygen consumption (EPOC, informally called afterburn) is a measurably increased rate of oxygen intake following strenuous activity. In historical contexts the term "oxygen debt" was popularized to explain or perhaps attempt to quantify anaerobic energy expenditure, particularly as regards lactic acid/ lactate metabolism; in fact, the term "oxygen debt" is still widely used to this day. However, direct and indirect calorimeter experiments have definitively disproven any association of lactate metabolism as causal to an elevated oxygen uptake. In recovery, oxygen (EPOC) is used in the processes that restore the body to a resting state and adapt it to the exercise just performed. These include: hormone balancing, replenishment of fuel stores, cellular repair, innervation, and anabolism. Post-exercise oxygen consumption replenishes the phosphagen system. New ATP is synthesized and some of this ATP donates phosphate groups to creatine until ATP and creatine lev ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aviation Medicine
Aviation medicine, also called flight medicine or aerospace medicine, is a preventive or occupational medicine in which the patients/subjects are pilots, aircrews, or astronauts. The specialty strives to treat or prevent conditions to which aircrews are particularly susceptible, applies medical knowledge to the human factors in aviation and is thus a critical component of aviation safety. A military practitioner of aviation medicine may be called a flight surgeon and a civilian practitioner is an aviation medical examiner. One of the biggest differences between the military and civilian flight doctors is the military flight surgeon's requirement to log flight hours. Overview Broadly defined, this subdiscipline endeavors to discover and prevent various adverse physiological responses to hostile biologic and physical stresses encountered in the aerospace environment. Problems range from life support measures for astronauts to recognizing an ear block in an infant traveling on an a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uncontrolled Decompression
Uncontrolled decompression is an unplanned drop in the pressure of a sealed system, such as an aircraft cabin or hyperbaric chamber, and typically results from human reliability, human error, fatigue (material), material fatigue, engineering failure, or impact (mechanics), impact, causing a pressure vessel to vent into its lower-pressure surroundings or fail to pressurize at all. Such decompression may be classed as ''explosive, rapid'', or ''slow'': * Explosive decompression (ED) is violent and too fast for air to escape safely from the lungs and other air-filled cavities in the body such as the Paranasal sinuses, sinuses and eustachian tubes, typically resulting in severe to fatal barotrauma. * Rapid decompression may be slow enough to allow cavities to vent but may still cause serious barotrauma or discomfort. * Slow or gradual decompression occurs so slowly that it may not be sensed before Hypoxia (medical), hypoxia sets in. Description The term ''uncontrolled decompression'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pressure Suit
A pressure suit is a protective suit worn by high-altitude pilots who may fly at altitudes where the air pressure is too low for an unprotected person to survive, even breathing pure oxygen at positive pressure. Such suits may be either full-pressure (e.g., a space suit) or partial-pressure (as used by aircrew). Partial-pressure suits work by providing mechanical counter-pressure to assist breathing at altitude. Background The region from sea level to around is known as the physiological-efficient zone. Oxygen levels are usually high enough for humans to function without supplemental oxygen and decompression sickness is rare. The physiological-deficient zone extends from to about . There is an increased risk of problems such as hypoxia, trapped-gas dysbarism (where gas trapped in the body expands), and evolved-gas dysbarism (where dissolved gases such as nitrogen may form in the tissues, i.e. decompression sickness). Above approximately oxygen-rich breathing mixture is req ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cabin Pressurization
Cabin pressurization is a process in which conditioned air is pumped into the cabin of an aircraft or spacecraft in order to create a safe and comfortable environment for passengers and crew flying at high altitudes. For aircraft, this air is usually bled off from the gas turbine engines at the compressor stage, and for spacecraft, it is carried in high-pressure, often cryogenic, tanks. The air is cooled, humidified, and mixed with recirculated air if necessary before it is distributed to the cabin by one or more environmental control systems. The cabin pressure is regulated by the outflow valve. While the first experimental pressurization systems saw use during the 1920s and 1930s, it was not until 1940 that a commercial aircraft would enter service with a pressurized cabin, when the Boeing 307 Stratoliner joined the Transcontinental & Western Air and Pan American Airways fleets. The practice would become widespread a decade later, particularly with the introduction of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Armstrong Limit
The Armstrong limit or Armstrong's line is a measure of altitude above which atmospheric pressure is sufficiently low that water boils at the normal temperature of the human body. Exposure to pressure below this limit results in a rapid loss of consciousness, followed by a series of changes to cardiovascular and neurological functions, and eventually death, unless pressure is restored within 60–90 seconds. On Earth, the limit is around above sea level, above which atmospheric air pressure drops below 0.0618 atm (6.3 kPa, 47 mmHg, or about 1 psi). The U.S. Standard Atmospheric model sets the Armstrong pressure at an altitude of . The term is named after United States Air Force General Harry George Armstrong, who was the first to recognize this phenomenon. Effect on body fluids At or above the Armstrong limit, exposed body fluids such as saliva, tears, urine, and the liquids wetting the alveoli within the lungs—but not vascular blood (blood within the circulatory syst ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Altimeter
An altimeter or an altitude meter is an instrument used to measure the altitude of an object above a fixed level. The measurement of altitude is called altimetry, which is related to the term bathymetry, the measurement of depth under water. The most common unit for altimeter calibration worldwide is hectopascals (hPa), except for North America (other than Canada ) and Japan where inches of mercury (inHg) are used. To obtain an accurate altitude reading in either feet or meters, the local barometric pressure must be calibrated correctly using the barometric formula. History The scientific principles behind the altimeter were first written by Alexander Bryce (minister), Rev. Alexander Bryce a Scottish minister and astronomer in 1772 who realised that the principles of a barometer could be adjusted to measure height. Pressure altimeter Altitude can be determined based on the measurement of atmospheric pressure. The greater the altitude, the lower the pressure. When a barometer is s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aerobic Exercise
Aerobic exercise (also known as endurance activities, cardio or cardio-respiratory exercise) is physical exercise of low to high intensity that depends primarily on the aerobic energy-generating process. "Aerobic" is defined as "relating to, involving, or requiring oxygen", and refers to the use of oxygen to meet energy demands during exercise via aerobic metabolism adequately. Aerobic exercise is performed by repeating sequences of light-to-moderate intensity activities for extended periods of time. Aerobic exercise may be better referred to as "solely aerobic", as it is designed to be low-intensity enough that all carbohydrates are aerobically turned into energy via mitochondrial ATP production. Mitochondria are organelles that rely on oxygen for the metabolism of carbs, proteins, and fats. Examples of cardiovascular or aerobic exercise are medium- to long-distance running or jogging, swimming, cycling, stair climbing and walking. History Archibald Hill, a British physiolo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as well as with other compounds. Oxygen is Earth's most abundant element, and after hydrogen and helium, it is the third-most abundant element in the universe. At standard temperature and pressure, two atoms of the element bind to form dioxygen, a colorless and odorless diatomic gas with the formula . Diatomic oxygen gas currently constitutes 20.95% of the Earth's atmosphere, though this has changed considerably over long periods of time. Oxygen makes up almost half of the Earth's crust in the form of oxides.Atkins, P.; Jones, L.; Laverman, L. (2016).''Chemical Principles'', 7th edition. Freeman. Many major classes of organic molecules in living organisms contain oxygen atoms, such as proteins, nucleic acids, carbohydrates, and fats, as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Federal Aviation Administration
The Federal Aviation Administration (FAA) is the largest transportation agency of the U.S. government and regulates all aspects of civil aviation in the country as well as over surrounding international waters. Its powers include air traffic management, certification of personnel and aircraft, setting standards for airports, and protection of U.S. assets during the launch or re-entry of commercial space vehicles. Powers over neighboring international waters were delegated to the FAA by authority of the International Civil Aviation Organization. Created in , the FAA replaced the former Civil Aeronautics Administration (CAA) and later became an agency within the U.S. Department of Transportation. Major functions The FAA's roles include: *Regulating U.S. commercial space transportation *Regulating air navigation facilities' geometric and flight inspection standards *Encouraging and developing civil aeronautics, including new aviation technology *Issuing, suspending, or revoking ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypobaric Chamber
A hypobaric chamber, or altitude chamber, is a chamber used during aerospace or high terrestrial altitude research or training to simulate the effects of high altitude on the human body, especially hypoxia (low oxygen) and hypobaria (low ambient air pressure). Some chambers also control for temperature and relative humidity. Procedure One or more subjects (usually, pilots or crew members, though anyone interested in the effects of high altitude can usually arrange a visit) are placed in the chamber. Before "ascending" to the desired altitude, subjects breathe oxygen from oxygen masks to purge nitrogen from their bloodstream so decompression sickness (DCS) does not occur. With masks in place, the atmospheric pressure inside the chamber is then reduced to simulate altitudes of up to tens of thousands of feet. The subjects then remove their oxygen masks and experience the symptoms of hypoxia. An inside safety observer, breathing oxygen by mask, should always be present to pla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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