The researchers found that the effect of altitude hypoxia on human sensory function appeared earlier, and vision was the most sensitive to hypoxia. Above 4300 meters above sea level, night vision is obviously damaged, and this damage will not be improved because of the compensatory reaction of the body or the decrease of altitude. The hearing function of human body will also be affected with the elevation. At an altitude of about 5,000 meters, people's high-frequency hearing will be reduced. From 5,000 meters to 6,000 meters, people's middle and low-frequency hearing will be significantly reduced, and the directional ability of hearing will also be significantly affected, which may also be an important reason for accidents under the condition of hypoxia at high altitude. In addition, the sense of touch and pain of the human body will gradually become dull when there is severe hypoxia, and illusions and hallucinations will appear at extreme heights.
In the aspect of memory influence, because memory is extremely sensitive to hypoxia, people's memory begins to be affected when the altitude is 1800 ~ 2400 meters; The memory is weak around 5000 meters, so it is impossible to remember two things at the same time; In the future, with the increase of altitude and the aggravation of hypoxia, it will show different degrees of memory damage, from memory decline to complete loss of memory ability. Researchers believe that memory impairment may be related to the functional changes of cholinergic system in hippocampus of brain. Hypoxia mainly affects short-term memory, but generally does not affect long-term memory.
Acute altitude hypoxia will seriously affect people's thinking ability. At the altitude of 1500m, people's thinking ability begins to be damaged, which shows that the newly learned ability of complex intellectual activities is affected. 3000 meters, all aspects of thinking ability decline, especially judgment. At 4000 meters, the handwriting is scrawled, the sentence is blunt and the grammar is wrong; Above 7000 meters, quite a few people can suddenly lose consciousness without obvious symptoms. Researchers believe that the harm of hypoxia to thinking ability lies in the contradiction between subjective feeling and objective damage. For example, hypoxia has caused significant damage to an individual's thinking ability, but he often doesn't realize it, and he won't notice it when he does something wrong. He also thinks that his thinking and working ability are "normal". In addition, people's attention will be significantly reduced during acute altitude hypoxia. When the altitude is above 5000 meters, it is difficult to concentrate, and they can't concentrate on one thing as usual. And with the increase of altitude and the aggravation of hypoxia, the scope of attention will become narrower and narrower.
The researchers pointed out that the special environmental characteristics of the plateau have obvious influence on the physiological and psychological activities of the body. The best way to combat hypoxia is to provide oxygen, such as providing a simple portable oxygen supply device for people entering the plateau for the first time, which will help to minimize the risk of cognitive decline caused by hypoxia. People have an adaptation process to hypoxia, which generally takes 1 ~ 3 months. Therefore, before entering the plateau for the first time, it is best to carry out exposure at different heights in a planned and intermittent manner, so that the body has enough time to compensate for environmental changes, thus alleviating and eliminating various symptoms caused by hypoxia.
What do you know about altitude hypoxia?
Tibet Plateau is called the roof of the world. The thin air and lack of oxygen in the plateau greatly affect the normal breathing of human beings.
Because the air density decreases with the increase of height, that is to say, the higher the height, the lower the air pressure. In order to facilitate the calculation, the conversion relationship between atmospheric pressure and altitude obtained from meteorology is adopted, and the average value of 760 mm Hg is used to represent the sea level pressure, so as to calculate the percentage of atmospheric pressure at various altitudes to sea level pressure, that is, the percentage of oxygen content at that altitude to that in plain areas.
Lhasa is 3649 meters above sea level, with oxygen content accounting for 64% of the plain, and Shiquan River is 4278 meters above sea level, with a percentage of 59%. Naqu is 4507 meters above sea level, accounting for 56%.
Countermeasures for altitude sickness (high nutrition)
I. Environmental characteristics of the plateau
1. Hypoxia
From the sea level to the altitude of 65438+ million meters, the oxygen content in the air is 2 1%. However, the air pressure decreases with the elevation, resulting in thin air, so the oxygen pressure also decreases. It is estimated that at an altitude of 4270 meters, the oxygen pressure is only 58% of the sea level. Therefore, although the relative proportion of oxygen in the atmosphere has not changed, because the air is thin, the absolute amount of oxygen decreases, leading to hypoxia.
Keep calm
According to meteorological measurement, the temperature will drop by 1 degree for every increase of150m. Generally, the temperature drops by 6.5 degrees for every increase of 1000 meters. Therefore, the temperature in the plateau area is colder than that in other areas of the same latitude.
3. Low humidity
The low humidity in the plateau increases the water discharged by the human body. According to the calculation, the water excreted by breathing on the plateau is 1.5 liters per day, and the water excreted through the skin is 2.3 liters, which is 1 times of the total body fluid excreted by the human body in the same latitude plain.
4. Strong sunlight radiation
At an altitude of 3600 meters, the ionizing radiation, ultraviolet intensity and skin penetration in the universe are three times that of sea level. In addition, the reflection of these lights through snow is also very strong. According to the measurement, snow can reflect 90% ultraviolet rays back to the surface, while the reflectivity of grassland is only 9%- 17%. In other words, due to the effect of accumulated snow, the human body will suffer from double radiation of ultraviolet rays.
The environmental characteristics of the plateau are really extraordinary. In this regard, the human body is not passive, but should make corresponding adjustments according to the environment. For short-term tourists, the adjustment is temporary, while people who have lived in the plateau for thousands of years have already formed adaptive changes. Let's see what changes people will experience in the plateau area.
1. Blood system
Two hours after entering the plateau, due to hypoxia, the body began to produce too many red blood cells to adapt to the hypoxic environment. Hemoglobin increased 1. 1 g every week. After about 6 weeks, the hemoglobin of human body will increase to about 20 g, which is about 1.4 times of the original. This phenomenon of high hemoglobin is very common in plateau areas, but after returning to low altitude areas, hemoglobin will gradually return to the original level, and mild anemia will occur after 3 weeks of continuous decline. Then the hemoglobin level will rise to normal. Therefore, it is not advisable to return to the plateau after returning to the low altitude area from the plateau for about 1 month, otherwise people with anemia are more likely to get altitude sickness.
2. Respiratory system
Due to the low oxygen pressure, the human body will hyperventilate and ventilate due to lack of oxygen. In the quiet state of sea level, the human body needs 250 ml of oxygen per minute, that is, 5 liters of air must be inhaled to exchange gas in the lungs. At an altitude of 3000 meters, the human body must inhale 7.5 liters of air to meet the body's demand for oxygen. At this time, people will feel short of breath, and if you add exercise, you will feel more tired.
However, living in the plateau is beneficial to the control of chronic bronchial asthma, which is similar to the principle of low-pressure oxygen chamber used to treat bronchial asthma, equivalent to the pressure in the area of 2000-2500 meters high. The plateau has four distinct seasons, low humidity, high ozone content in the air and high solar radiation intensity, which is beneficial to the rehabilitation of asthma patients. In fact, local residents seldom suffer from respiratory diseases.
3. Circulation system
Due to lack of oxygen, tourists are generally emotional, and their hearts will beat faster with a little exercise. When you first arrive at the plateau, your morning pulse (the pulse when you wake up in the morning) is about 20% higher than the sea level. 10 days later, the morning pulse should drop to the original level. Therefore, by measuring the change degree of morning pulse and the time to return to the original level, we can judge the adaptability of human body to plateau. The incidence of coronary heart disease, arteriosclerosis, hypertension, diabetes, obesity and other diseases in plateau area is very low, and the blood cholesterol and triglyceride levels of local people are also very low.
4. Immune system
In plateau environment, T lymphocytes, which play an important role in human immunity, will be damaged, making the body very vulnerable to bacterial infection.
5. Reproductive system
When men are at an altitude of 4300 meters, the number and fluidity of sperm are obviously reduced, and the morphology of sperm is abnormally increased. But don't worry, it's only temporary. This phenomenon can gradually return to normal when we return to low altitude.
When women are at an altitude of 4300 meters, the incidence of dysmenorrhea and menstrual disorders increases. Spontaneous abortion, premature delivery and congenital malformation are very common, which is one of the reasons why the population birth rate in snowy plateau has been relatively low. Of course, these situations are not a problem for tourists.
Third, look at altitude sickness
After entering the plateau area, the human body will make corresponding adjustments according to environmental changes. However, the short stay of tourists will limit the adjustment range of the human body, so altitude sickness may still occur. The following are the main points of identifying altitude sickness. Remember, once you find that you may have altitude sickness, the first thing to do is to go to the hospital quickly. Many altitude sickness are very dangerous and must be treated in time.
1. Acute altitude sickness
It most often occurs on the first day and the second day of entering the plateau above 3300 meters above sea level, especially in the first 6-9 hours.
Identification points: headache, plus any of the following symptoms: general fatigue, dizziness, insomnia, nausea, vomiting.
2. High altitude pulmonary edema
The mortality rate of untreated high altitude pulmonary edema is 40%.
Key points of identification: those with the following two or more conditions: dyspnea, cough, fatigue and decreased activity, chest congestion, pale and cyanotic skin, and increased heart rate.
3. Alpine brain edema
The fatality rate of untreated mountain brain edema was 65438 04%.
Key points of identification: symptoms of acute mountain sickness, inability to walk in a straight line and mental abnormality.
4. Chronic altitude sickness
Refers to the adaptation to the plateau environment for a period of time, and the inadaptability to the plateau environment reappears.
Identification points: fatigue, headache, dizziness, cyanosis, lack of endurance during exercise, etc.
5. Others
At different altitudes, tourists may have the following symptoms:
1500m: vision loss in the dark.
1500-1800m: the advanced thinking function is weakened or missing.
3300 meters: Simple arithmetic becomes difficult.
4600 meters: writing and thinking are affected.
Above 5500m: 100% tourists will suffer from pharyngitis and tracheitis.
Fourth, preparation before entering the plateau
1. From the day you decide to travel to the plateau, you should increase the time of anaerobic exercise in your daily life. Anaerobic exercise refers to strenuous exercise with a large amount of exercise, which can make the body have a certain tolerance to hypoxia.
2. Prepare some commonly used medicines. In plateau areas, the respiratory system is very susceptible to infection, and antibiotics such as amoxicillin and roxithromycin should be brought. The sanitary conditions in plateau are limited, and it is easy to suffer from gastroenteritis. You can bring ciprofloxacin or sulfonamides. Also need to prepare diuretic acetazolamide, which is the main drug to prevent altitude sickness, can eliminate paroxysmal nocturnal apnea, improve the quality of nighttime sleep, and relieve the headache when getting up in the morning. Administration method: 125mg twice a day or 250mg once a day. Take it 24 hours before entering the plateau.
3. The temperature difference between morning and evening in plateau area can reach 15-20 degrees, so it is necessary to bring enough cold-proof clothes.
4. Prepare protective articles against ultraviolet rays.
5. If you fly directly into the plateau area, you should get enough sleep the night before sailing in the low altitude area, and don't eat greasy food and drinks. If you enter the plateau area by car or train, you should make a good daily travel plan, and the rising height should be controlled at 400-600 meters every day. Every time you reach a new height, you should rest for a few days, so that your physical strength can gradually recover and adapt to the anoxic environment on the plateau. If you are hiking or riding a bike, please ask an expert to make a scientific mountaineering plan in advance according to your physical condition.