Man first flew into space in 1961, but even half a century later there are no exact answers to the questions about how exactly space flight and prolonged stay in conditions of minimal gravity or zero gravity affects the human body.
In a new study, scientists decided to study the changes in the body of astronauts a little deeper, almost at the molecular level.
Irreversible changes
A study of the health status of astronauts after a long stay in space showed that there are a number of changes that strongly affect their health both during the flight and after. Many astronauts, after a period of time spent in zero gravity, cannot return to their previous indicators of physical fitness.
This is because microgravity conditions strain the human body and lead to its weakening. For example, the heart weakens due to loss of mass, since in weightlessness the blood is distributed differently and the heart beats more slowly.
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In addition, bone density is reduced because the body is not affected by Earth's gravity. Changes in bone mass are observed already in the first two weeks in zero gravity, and after a long stay in space, it is almost impossible to restore the previous state of the tissue.
Changes in the body's immune system and in the metabolic process are especially strong.
The immune system
Immunity suffers from the fact that weightlessness is an extremely new state for humans in terms of evolutionary development. For hundreds of thousands of years, people have not encountered the conditions of microgravity and were extremely genetically unprepared for them.
Because of this, the immune system perceives weightlessness as a threat to the whole body and tries to activate all possible defense mechanisms at once.
In addition, in conditions of isolation from the usual conditions, the human body is faced with a minimum number of bacteria, viruses and microbes, which also negatively affects immunity.
Metabolism
Metabolic changes occur for a number of reasons. First, the body's endurance decreases and muscle mass is lost due to the lack of physical exertion, to which the body is accustomed to gravity.
Secondly, due to reduced endurance and aerobic activity, the body consumes less oxygen and breaks down less fat.
Third, due to changes in the cardiovascular system, less oxygen enters the muscles through the blood.
All this suggests that the human body is going through a difficult period of adaptation to the conditions of a long stay in space. However, how exactly and why do changes occur in the body?
Study of blood composition
The study of the state of astronauts before, during and after space missions showed that there are changes in the immune system, muscle tone, metabolic processes and regulation of body temperature, but scientists still do not understand the mechanisms that stimulate these changes.
In a new report published in Scientific Reports, Canadian and Russian scientists have come to the conclusion that the answer to this question can be found by studying one of the main components of our body - proteins.
It turns out that space flight reduces the content of various protein groups in the human body. Some of them quickly return to normal, while others find it much more difficult to come to a pre-flight state.
Research progress
To study the effect of prolonged stay in orbit in microgravity on the protein content in the blood, scientists studied the blood plasma of 18 Russian cosmonauts who had been on long-term missions to the International Space Station.
The first sample of plasma was collected one month before the flight, the second sample was collected immediately after landing, and the final sample was collected one week after the completion of the mission.
In certain cases, astronauts themselves took and studied samples while on the ISS to provide more accurate indicators of how the content of certain proteins in their blood changes.
results
Only 24% of the analyzed protein groups were found in lower levels immediately after landing on Earth and after seven days.
Certain protein groups were found to be low immediately upon landing, but quickly bounced back within a week.
conclusions
The study of the difference in the maintenance of proteins in the blood is one of the ways that can be used to explain some of the changes occurring in the body of an astronaut who has been in zero gravity for a long time.
For example, the authors of the study concluded that virtually all 24% of the proteins that changed in concentration during their stay in space were associated with just a few body processes, such as fat metabolism, blood clotting and immunity.
Hope Chikanchi