Travel to space has become commonplace. People live on orbital stations for several months a time. But humans are prepared for life on Earth, not in space. What changes occur in the body of those who stay on Earth orbit for a long time? What achievements of space medicine do we use here on earth?
A person's ability to hold the upright posture depends on the brain neurons involved in the maintenance of balance and orientation in space. People caught up in orbit first have completely disrupted coordination of movements. On Earth, people are used to resisting the force of gravity. When on Earth we stretch our arms, our muscles also perform work resisting gravity. It does not exist in space, however, although the muscles continue to perform their usual work. As a result, the arm moves not only forward but also up.
The heart due to earth's gravity distributes blood to all our extremities. In weightlessness, the blood is concentrated in the upper part of the body. Because of that people swell and there are even changes in the tongue as it thickens and the taste buds no longer properly transmit sensations. Perhaps this is why the astronauts on board frequently ask for salty foods.
Solid formations on the mechanoreceptor cells of organs of equilibrium may provoke a loss of orientation in space. Today there are no methodologies for facilitating the adaptation process in the absence of gravity.
There is another enemy of the astronauts - radiation. The body of the space station is protected from radiation, but no one knows for how long this protection can stop the powerful rays of ultraviolet. Being in such circumstances can lead to cancer. Getting a lethal dose of radiation on the orbit is very easy. Therefore when preparing for long-term mission this has to be considered.
On board the ISS there is a real human skeleton. It is used to study the effects of harmful radiation on the human body. It had been in space for more than a year. The astronauts call it a "doll" as it has organs attached to the bones made of material similar in structure to human skin. The skeleton has thousands of dosimeters, so all data on the impact is given to the researchers.
The work of the digestive tract depends on the food menu so the astronauts have to be balanced in all parameters: nutrients, salts, and vitamins. There is a basic diet formed in half of Russian products, and other half of the U.S. foods. There are also additional foods chosen considering the tastes of each crew member, and each time range. Officially alcohol on board is not allowed.
Despite the best efforts of doctors, food is the item that always annoys astronauts. They get quickly bored with the food offered on flight.
The problem with zero gravity also affects intestinal motility, which depends on mechanical factors, i.e., not only the content but also the weight of the food. Motility is closely monitored by the astronauts. They take bifidobacteria, nutritional supplements, and dietary fiber.
One of the most important devices on the spacecraft is a toilet. If it breaks down, then there are great difficulties. Russian toilet has never been broken, as opposed to those on the U.S. shuttles.
A crucial point in the training for space missions is psychological stability and testing the ability to deals with serious stress load. The European Training Center for the astronauts offers a variety of role playing exercises. These exercises are designed, for instance, to resolve a conflict situation. Each participant is prepared a program based of their psychological characteristics. Experts are looking at how they are coping with stress.
In the flight, people are rarely left alone, but there is such a possibility. Despite the fact that there are normally only two cabins on the ship and more people, there are specially equipped places where a person can be alone.
Sleep is a very fragile thing. If a person is nervous or worried about problems, it affects their sleep. Sleep in weightlessness is no different than on Earth according to the astronauts who visited the orbit.
Sexual health and function of the reproductive system of the astronauts completely recover after the flight.
The biggest issue for astronauts is problems with bone and muscle mass. When a person is standing, over 100 muscles are working. In space, there is no pressure on the muscles, and they begin to atrophy. Loss of muscle volume and bone mass may be slowed down with the ongoing exercise, therefore astronauts spend at least 2 hours a day at the gym. However, it is impossible to completely get rid of the problems of loss of muscle mass. There are muscles that work only in gravity, and no artificial stress can make them work.
Bone and joints also suffer. If they are not subjected to stress, they become thinner and osteoporosis develops, which leads to increased bone fragility. Doctors understand the danger and are very cautious about the state of the bone structure of the astronauts. Unfortunately, it is not yet possible to completely stop the process of osteoporosis. Measures aimed at preventing the disease can bring only temporary relief. It is difficult to go back to the state of bone health the astronauts had before the flight and not everyone succeeds.
The inaptness of the human body to the rigors of space did not become an obstacle in the exploration of outer space. It is difficult to list all the developments that have been initially made for space but are currently successfully used on Earth.
For example, modern medicine seeks to ensure that the devices are mobile, because it is more convenient to bring such devices to the patient, and not vice versa. In this respect, the experience of doctors working with the astronauts is priceless. Of course, the use of medical technology at a distance, the so-called telemedicine, is an idea that came from medical practice for professionals working with the astronauts. For example, the doctor can be in one city, and the patient is in another. Telemedicine is used for diagnostics and operations by the doctors who, for example, cannot get into the area of major natural disasters.
Incidentally, the famous bifidobacteria were originally invented for use in the space.