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Death Zone
In mountaineering, the death zone refers to altitudes above a certain point where the pressure of oxygen is insufficient to sustain human life for an extended time span. This point is generally tagged as , less than 356 millibars of atmospheric pressure). The concept was conceived in 1953 by Edouard Wyss-Dunant, a Swiss doctor, who called it the lethal zone. All 14 peaks above 8000 m in the death zone are located in the Himalaya and Karakoram of Asia. Many deaths in high-altitude mountaineering have been caused by the effects of the death zone, either directly by loss of vital functions or indirectly by wrong decisions made under stress, or physical weakening leading to accidents. An extended stay above without supplementary oxygen will result in deterioration of bodily functions and death. Physiological background The human body has optimal endurance below elevation. The concentration of oxygen (O2) in air is 20.9% so the partial pressure of O2 (PO2) at sea level is abo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Everest Kalapatthar Crop
Mount Everest (; Tibetic languages, Tibetan: ''Chomolungma'' ; ) is List of highest mountains on Earth, Earth's highest mountain above sea level, located in the Mahalangur Himal sub-range of the Himalayas. The China–Nepal border runs across its summit, summit point. Its elevation (snow height) of was most recently established in 2020 by the Chinese and Nepali authorities. Mount Everest attracts many climbers, including highly experienced mountaineers. There are two main climbing routes, one approaching the summit from the southeast in Nepal (known as the "standard route") and the other from the north in Tibet. While not posing substantial technical climbing challenges on the standard route, Everest presents dangers such as altitude sickness, weather, and wind, as well as hazards from avalanches and the Khumbu Icefall. , over 300 people have List of people who died climbing Mount Everest, died on Everest, many of whose bodies remain on the mountain. The first recor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digestive System
The human digestive system consists of the gastrointestinal tract plus the accessory organs of digestion (the tongue, salivary glands, pancreas, liver, and gallbladder). Digestion involves the breakdown of food into smaller and smaller components, until they can be absorbed and assimilated into the body. The process of digestion has three stages: the cephalic phase, the Regulation of gastric function#Gastric phase, gastric phase, and the Regulation of gastric function#Intestinal phase, intestinal phase. The first stage, the cephalic phase of digestion, begins with secretions from gastric glands in response to the sight and smell of food. This stage includes the mechanical breakdown of food by chewing, and the chemical breakdown by digestive enzymes, that takes place in the human mouth, mouth. Saliva contains the digestive enzymes amylase, and lingual lipase, secreted by the salivary gland, salivary and serous glands on the tongue. Chewing, in which the food is mixed with saliva ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
George Finch (chemist)
George Ingle Finch (4 August 1888 – 22 November 1970) was an Australian chemist and mountaineer. He was the first person known to climb to a height exceeding 8,000 metres. His obituary in The Times describes him as "one of the two best alpinists of his time" (with George Mallory). Education and military service He was born in Australia to Charles Edward and Laura Isabel (nee Black) Finch, educated in German-speaking Switzerland, and studied physical sciences at the University of Geneva. He began studying medicine in Paris (where he scaled the walls of Notre Dame with his brother) but decided he preferred the physical sciences. During the First World War, he served with the Royal Army Ordnance Corps. He was appointed a Member of the Order of the British Empire in the 1918 New Year Honours for services in connection with the War in France, Egypt and Salonika. In the Second World War he investigated fire defence. Career A member of the second British expedition under Gene ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1921 British Mount Everest Reconnaissance Expedition
The 1921 British Mount Everest reconnaissance expedition set off to explore how it might be possible to get to the vicinity of Mount Everest, to reconnoitre possible routes for ascending the mountain, and – if possible – make the first ascent of the highest mountain in the world. At that time Nepal was closed to foreigners, so any approach had to be from the north, through Tibet. A feasible route was discovered from the east up the Kharta Glacier and then crossing the Lhakpa La pass north east of Everest. It was then necessary to descend to the East Rongbuk Glacier before climbing again to Everest's North Col. However, although the North Col was reached, it was not possible to climb further before the expedition had to withdraw. Initially the expedition explored from the north and discovered the main Rongbuk Glacier, only to find that it seemed to provide no likely routes to the summit. However, at the time it was not realised that the East Rongbuk glacier actually fl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chronic Mountain Sickness
Chronic mountain sickness (CMS) is a disease in which the proportion of blood volume that is occupied by red blood cells increases (polycythaemia) and there is an abnormally low level of oxygen in the blood (hypoxemia). CMS typically develops after extended time living at high altitude (over ). It is most common amongst native populations of high altitude nations. The most frequent symptoms of CMS are headache, dizziness, tinnitus, breathlessness, palpitations, sleep disturbance, fatigue, loss of appetite, confusion, cyanosis, and dilation of veins. CMS was first described in 1925 by Carlos Monge Medrano, a Peruvian doctor who specialised in diseases of high altitude. While acute mountain sickness is experienced shortly after ascent to high altitude, chronic mountain sickness may develop only after many years of living at high altitude. In medicine, high altitude is defined as over , but most cases of CMS occur at over . It has recently been correlated with increased expression of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypoxia (medical)
Hypoxia is a condition in which the body or a region of the body is deprived of adequate oxygen supply at the tissue level. Hypoxia may be classified as either '' generalized'', affecting the whole body, or ''local'', affecting a region of the body. Although hypoxia is often a pathological condition, variations in arterial oxygen concentrations can be part of the normal physiology, for example, during strenuous physical exercise.. Hypoxia differs from hypoxemia and anoxemia, in that hypoxia refers to a state in which oxygen present in a tissue or the whole body is insufficient, whereas hypoxemia and anoxemia refer specifically to states that have low or no oxygen in the blood. Hypoxia in which there is complete absence of oxygen supply is referred to as anoxia. Hypoxia can be due to external causes, when the breathing gas is hypoxic, or internal causes, such as reduced effectiveness of gas transfer in the lungs, reduced capacity of the blood to carry oxygen, compromised gene ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HACE
High-altitude cerebral edema (HACE) is a medical condition in which the brain swells with fluid because of the physiological effects of traveling to a high altitude. It generally appears in patients who have acute mountain sickness and involves disorientation, lethargy, and nausea among other symptoms. It occurs when the body fails to acclimatize while ascending to a high altitude. It appears to be a vasogenic edema (fluid penetration of the blood–brain barrier), although cytotoxic edema (cellular retention of fluids) may play a role as well. Individuals with the condition must immediately descend to a lower altitude or coma and death can occur. Patients are usually given supplemental oxygen and dexamethasone as well. HACE can be prevented by ascending to heights slowly to allow the body more time to acclimatize. Acetazolamide also helps prevent the condition. Untreated patients usually die within 48 hours. Those who receive treatment may take weeks to fully recover. It is a rar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cerebral Edema
Cerebral edema is excess accumulation of fluid ( edema) in the intracellular or extracellular spaces of the brain. This typically causes impaired nerve function, increased pressure within the skull, and can eventually lead to direct compression of brain tissue and blood vessels. Symptoms vary based on the location and extent of edema and generally include headaches, nausea, vomiting, seizures, drowsiness, visual disturbances, dizziness, and in severe cases, coma and death. Cerebral edema is commonly seen in a variety of brain injuries including ischemic stroke, subarachnoid hemorrhage, traumatic brain injury, subdural, epidural, or intracerebral hematoma, hydrocephalus, brain cancer, brain infections, low blood sodium levels, high altitude, and acute liver failure. Diagnosis is based on symptoms and physical examination findings and confirmed by serial neuroimaging ( computed tomography scans and magnetic resonance imaging). The treatment of cerebral edema depends ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HAPE
High-altitude pulmonary edema (HAPE) is a life-threatening form of non-cardiogenic pulmonary edema that occurs in otherwise healthy people at altitudes typically above . However, cases have also been reported between in more vulnerable subjects. Classically, HAPE occurs in persons normally living at low altitude who travel to an altitude above 2,500 meters (8,200 feet). Re-entry HAPE is also an entity that has been described in persons who normally live at high altitude but who develop pulmonary edema after returning from a stay at low altitude. It is severe presentation of altitude sickness. There are many factors that can make a person more susceptible to developing HAPE, including genetic factors, but detailed understanding is lacking and currently under investigation. HAPE remains the major cause of death related to high-altitude exposure, with a high mortality rate in the absence of adequate emergency treatment. Signs and symptoms Physiological and symptomatic changes oft ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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