Search results
Results From The WOW.Com Content Network
However, the human body has both short-term and long-term adaptations to altitude that allow it to partially compensate for the lack of oxygen. There is a limit to the level of adaptation; mountaineers refer to the altitudes above 8,000 metres (26,000 ft) as the death zone, where it is generally believed that no human body can acclimatize.
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 ...
The human body has optimal endurance below 150 m (490 ft) elevation. [6] The concentration of oxygen (O 2) in air is 20.9% so the partial pressure of O 2 (PO 2) at sea level is about 21.2 kPa (6.3 inHg; 3.07 psi). In healthy individuals, this saturates hemoglobin, the oxygen-binding red pigment in red blood cells. [7]
High-altitude adaptation in humans is an instance of evolutionary modification in certain human populations, including those of Tibet in Asia, the Andes of the Americas, and Ethiopia in Africa, who have acquired the ability to survive at altitudes above 2,500 meters (8,200 ft). [1]
Country codes are defined by the International Telecommunication Union (ITU) in ITU-T standards E.123 and E.164. The prefixes enable international direct dialing (IDD). Country codes constitute the international telephone numbering plan. They are used only when dialing a telephone number in a country or world region other than the caller's.
Area codes 778, 236, and 672 are telephone area codes in the North American Numbering Plan (NANP) for the Canadian province of British Columbia.They form an overlay complex with area code 604, which serves only a small southwestern section, the Lower Mainland, of the province (including Vancouver), and area code 250, which serves the rest of the province.
For international access the NANP is assigned the country code 1, which is dialed as a prefix in the international E.164 telephone numbering plan. The trunk prefix for dialing long-distance calls, across numbering plan area (NPA) boundaries within Canada or to other NANP countries, is also 1.
Quebec City. Area codes 418, 581, and 367 are telephone area codes in the North American Numbering Plan (NANP) for the eastern portion of the Canadian province of Quebec.Area code 418 was originally assigned to the numbering plan area, but all three area codes now form an overlay plan for this territory.