How does weightlessness affect the health of astronauts?
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Becoming an astronaut is a popular childhood dream. It seems that space travel is something incredible and fantastic. This is true, but the work of an astronaut is associated with a large number of difficulties and dangers that are unknown to an ordinary person. The lack of gravity alone has a profound effect on the body. How does the body change in a state of weightlessness? One of the most interesting is the change in human height. Under gravity, the muscles ensure that the vertebrae adhere to each other, thereby maintaining the correct curvature of the spine. In zero gravity, muscles gradually weaken and atrophy. As a result, growth can increase by several centimeters. Any changes in the body are very important for astronauts. For example, the landing capsule contains a cradle - a special device that is made individually for each individual.
The lodgement must fully comply with the parameters of the astronaut, otherwise his safety is threatened during landing on Earth.
To avoid such problems, astronauts wear special suits - "Penguins". The main task of such a suit is to create a load on the musculoskeletal system, to reduce the effect of weightlessness. "Penguin" cosmonaut's suit It must not be forgotten that the heart is also a muscle, which means that weightlessness affects it in the same way. It has long been proven that in the absence of gravity, the heart becomes weaker and loses volume. But NASA studies have shown another change - the rounding of the heart shape. This study was attended by 12 astronauts who worked on the ISS. It turned out that the human heart becomes 9.4% rounder. When the astronaut returns to normal conditions, the muscle gradually regains its normal shape. To make it easier to understand the effect on the heart, one can imagine that one week in zero gravity is the same as 1.5 months of constant bed rest.
many ordinary things in space become impossible. For example, an astronaut is not able to cry and thus get rid of stress, negative emotions, etc. With gravity, tears roll down, but if it is not there, then salty drops remain inside the eye or gradually accumulate under it, interfere with vision and cause an unpleasant burning sensation. Cosmonauts get rid of moisture using special devices.
The aging process is also activated in space. Even in spite of the negative processes in the musculoskeletal system, changes occur with the endothelial cells in zero gravity. They are located inside all vessels, which causes an effect on the cardiovascular system. Scientists insist that it was thanks to gravity that human evolution took place, and in the absence of gravity, body tissues age very quickly. Succumb to the harmful effects of weightlessness and bone. This happens for several reasons, such as a lack of bone material, impaired phosphorus metabolism, and a decrease in the amount of calcium. The body understands that there is no need to support the body, and all these processes are suspended. As a result, within 30 days of being in space, a person can lose 1-2% of bone mass. The destruction of bones even has a separate term - space osteopathy.
Upon returning to Earth, the cosmonaut gradually restores the volume of bone mass. At the same time, it is important that the stay in space does not take too long, since recovery will be impossible at critical rates (with a loss of 50% of bone mass, for example). It is vital for astronauts to perform various training exercises during space flight. For this, special simulators are used that ensure the attraction of the body and the load on the body. These include treadmills, strength training simulators, bicycle simulators, etc. Also, cosmonauts undergo thorough flight training in specialized centers. Research on the effects of space on the body Scientists have also found through experiments and research that being in zero gravity affects the body's immune system. In other words, a person is more susceptible to various diseases, since his immunity worsens. In simple terms, the essence of the immune system is to find a foreign microorganism in the body and attack it. The research was carried out by a team of NASA scientists with the involvement of 23 astronauts (men and women) aged about 53 years. The cosmonauts were in zero gravity for a different amount of time. They did the necessary tests before departure, some of the participants in the experiment took their blood while at the station. Then surveys were carried out upon the arrival of the cosmonauts on Earth immediately and after certain intervals. Thus, we were able to compare the results and find out that the immunity of astronauts who worked on the ISS for six months significantly deteriorated compared to the rest of the research participants. In particular, the ability of the immune system to recognize a threat and to eliminate it has significantly decreased. Upon the return of the cosmonauts to Earth, the immune system began to slowly recover. The exact reason for such changes has not been established, since it can be stress, disruption of the biological clock, being in zero gravity.
Another study was conducted on the effect of weightlessness on the skin of the body. Astronauts often complained of skin itching and dryness. For the experiment, mice were sent into orbit for a period of three months. A survey of rodents returning from space showed that the skin was thinned by 15%, and the growth of the coat also changed. Moreover, the changes took place at the level of genes. An interesting fact: with the help of mice, the effect of weightlessness on vision was also established. They were sent into outer space for a month, after which the condition of their eyes was analyzed. Scientists have found that vision deteriorates due to impaired activity of blood vessels. It is natural for the organism of all living beings that the blood rushes to the legs under the influence of gravity. In zero gravity, it puts pressure on the brain, which damages the work of blood vessels.

Astronauts working on the ISS often complain of visual impairment. Upon their arrival on Earth, vision also gradually returns to its previous state, but, as in the case of other organs and systems, it all depends on the duration of their stay in space. Scientists are actively looking for solutions that will help reduce the effect of weightlessness on the human body. Weightlessness is unusual for the human body. Many of its systems are dependent on the force of gravity, so the absence of gravity negatively affects the health of astronauts. The work of the musculoskeletal system, the cardiovascular system deteriorates, muscles, vision, immunity, and skin condition weaken. The harmful effect of weightlessness depends on how long the astronaut stays in space. For the prevention of various diseases and problems, special equipment is used, and the astronauts are carefully preparing to be sent into space.
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