The factors that have the most significant effect on the state of the human body in space flights include: 1) accelerations and overloads caused by them in active flight phases (during takeoff of a spacecraft and during descent); 2) weightlessness; 3) stressful influences, in particular emotional.
In addition, the state of the astronauts is influenced by changes in the rhythm of the daily period, sensory isolation to varying degrees, a closed habitat with microclimate features, periodically some dustiness of the artificial atmosphere of a spacecraft, noise, vibration, etc. The impact of ionizing radiation is taken into account when providing spacecraft with radiation protection, when planning manned space walks.
Acceleration, overload. Accelerations are expressed at the beginning of the flight during takeoff of the spacecraft and at the end of the flight during the descent of the spacecraft from orbit (entry into the dense layers of the atmosphere and landing).
Acceleration is a vector quantity that characterizes the speed of changes in the speed of movement or direction of movement. The amount of acceleration is expressed in meters per second squared (m / s 2). When moving with acceleration in the opposite direction, the inertial force acts. For its designation, the term is used "overload". The magnitudes of the overloads, as well as the magnitudes of the accelerations, are expressed in relative units, denoting how many times the body weight increases at a given acceleration in comparison with the weight under conditions of ordinary earth's gravity (under conditions of static rest or uniform rectilinear motion). The magnitudes of accelerations and overloads are denoted by the letter G - the initial letter of the word "gravity" (attraction, gravity). The magnitude of the earth's gravity is taken as a relative unit. At
free fall of a body in an airless space, it causes an acceleration of 9.8 m / s 2. At the same time, under conditions of gravity, the force with which the body presses on the support and experiences opposition from it is designated as weight. In aviation and space medicine, overloads are distinguished by a number of indicators, including the magnitude and duration (long-term
More than 1 s, percussion - less than 1 s), the speed and nature of the rise (uniform, peak-like, etc.). According to the ratio of the overload vector to the longitudinal axis of the human body, longitudinal positive (in the direction from head to legs), longitudinal negative (from legs to head), transverse positive (chest
- back), transverse negative (back-chest), lateral positive (right to left) and lateral negative (left to right).
Significant overloads cause redistribution of blood mass in the vascular bed, impaired lymph outflow, displacement of organs and soft tissues, which primarily affects blood circulation, respiration, and the state of the central nervous system. The movement of a significant mass of blood is accompanied by the overflow of the vessels of some regions of the body and the exsanguination of others. Correspondingly, the return of blood to the heart and the amount of cardiac output change, reflexes from the baroreceptor zones are realized, which take part in the regulation of the work of the heart and vascular tone. A healthy person most easily tolerates transverse positive overloads (in the chest-back direction). The majority of healthy persons freely tolerate uniform overloads in this direction of up to 6-8 units for one minute. With short-term peak overloads, their tolerance increases significantly.
With transverse overloads exceeding the limit of individual tolerance, the function of external respiration is disrupted, the blood circulation in the vessels of the lungs changes, and the contractions of the heart sharply increase. With an increase in the magnitude of transverse overloads, mechanical compression of individual sections of the lungs, impaired blood circulation in a small circle, and a decrease in blood oxygenation are possible. At the same time, due to the deepening of hypoxia, the increase in heart rate is replaced by a slowdown.
Harder than transverse
Part I. GENERAL NOSOLOGY
longitudinal overloads are transferred. With positive longitudinal overloads (in the direction from the head to the legs), it becomes difficult for blood to return to the heart, the blood filling of the heart cavities and, accordingly, cardiac output decreases, the blood supply of the vessels of the cranial parts of the body and the brain decreases. The receptor apparatus of the synocartid zones responds to a decrease in blood pressure in the carotid arteries. As a result, tachycardia occurs, in some cases, heart rhythm disturbances appear. When the limit of individual resistance is exceeded, pronounced arrhythmias of the heart, visual disturbances in the form of a veil, breathing disorders, and pain in the epigastric region appear. Tolerance of longitudinal positive G-forces in most cases is within 4-5 units. However, even with an overload of 3 units, in some cases, pronounced cardiac arrhythmias occur.
Longitudinal negative overloads are even more difficult to bear (in the direction of the leg - the head). In these cases, the blood vessels of the head overflow with blood. An increase in blood pressure in the reflexogenic zones of the carotid arteries causes a reflex slowdown of heart contractions. With this type of overload, cardiac arrhythmias in some cases are noted already at accelerations of 2 units, and prolonged asystole - at acceleration of 3 units. When the limits of individual stability are exceeded, headache, visual disturbances in the form of a veil before the eyes, cardiac arrhythmias occur, breathing is disturbed, a fainting state occurs, and then loss of consciousness occurs.
The tolerance of g-forces depends on many conditions, including the magnitude, direction and duration of accelerations, the nature of their growth, the position of the human body and its fixation, fitness, individual reactivity, etc. The flight conditions of modern spacecraft, the optimal position of the astronaut in relation to the acceleration vector allow avoid the adverse effects of overloads, but their impact increases in emergency situations and under so-called abnormal landing conditions.
Weightlessness. The study of the effect of weightlessness on the human body is one of the most
The most intensively developing directions of modern gravitational biology over the past two decades (the science of the influence of gravity on the development of life, the formation of structures and functions of the body, the effect of altered gravity on the course of adaptation processes in normal and extreme conditions).
The state of weightlessness occurs under certain conditions. According to Newton's law of universal gravitation, any two material particles are attracted to each other with a force directly proportional to the product of their masses and inversely proportional to the square of the distance between them:
t 1 t g
F = G-------------- .
The founder of the modern science of space flight KE Tsiolkovsky defined weightlessness as a state in which the forces of gravity "do not act at all on the observed bodies or act on them very weakly ...". The state of weightlessness can arise in various situations, in particular, when in outer space, due to the great distance from the Earth, a body practically does not experience gravity, or when the force of gravity is balanced by the attraction of other celestial bodies (static weightlessness). In other cases, weightlessness occurs when the action of the force of gravity (decrease due to distance from the Earth) is balanced by oppositely directed centrifugal forces (dynamic weightlessness).
In orbital space flight, bodies move mainly under the influence of inertial force (with the exception of short periods of operation of jet engines to correct the flight trajectory). In orbital flight, the inertial force is balanced by the Earth's gravity. This determines the state of weightlessness of the spacecraft and all objects moving with it. Weightlessness is also referred to as the state of "zero gravity". In zero gravity, the body, freed from the action of gravity, must adapt to new unusual conditions, which determines a complex multi-link adaptation
ny process. In connection with zero gravity in weightlessness, mechanical stress and compression of body structures immediately disappear to the extent that this was due to its weight, and accordingly the load on the musculoskeletal system changes: the weight of the blood disappears and, consequently, the hydrostatic pressure of the fluid in the blood vessels ; conditions arise for a significant redistribution of blood in the vascular bed and fluid in the body; the feeling of support disappears; the conditions of functioning of the analyzer systems reacting to the direction of gravity are changing; there is a mismatch in the activities of various departments of the vestibular analyzer. These changes determine many interrelated deviations in the state of functional systems, accompanied by the development of adaptive processes that occur at various levels of the whole organism with a change in cause-effect relationships.
Changes in blood circulation in weightlessness are due to several factors. Under terrestrial gravity, the transport of fluid through the walls of the capillaries according to the Sterling equation is determined by the ratios of the hydrostatic and colloidal-osmotic pressure in the capillaries and the tissues surrounding them. Moreover, in many regions of the body, as the hydrostatic pressure decreases in the direction from the arterial end of the capillary to the venous end, the filtration of fluid from the vessels into the tissue is replaced by its reabsorption from the tissues into the vessels. Accordingly, the filtration-reabsorption ratios at the microcirculatory level change. This is manifested in an increase in fluid absorption at the level of capillaries and venules and is one of the factors causing an increase in the volume of circulating blood at the beginning of the flight and dehydration of tissues in certain regions of the body (mainly legs). The height of the liquid column ceases to affect the pressure in both small and large blood vessels. In zero gravity conditions, it depends on the pumping and suction functions of the heart, elastic-viscous properties of the walls of blood vessels and the pressure of the surrounding tissues.
In zero gravity, the differences in venous pressure in the vessels of the forearms and legs are smoothed out. The assumption of an increase in central venous pressure during flights was not confirmed.
Moreover, it turned out that in zero gravity it decreases. The loss of blood weight makes it easier for blood to move from the veins of the lower half of the body to the heart. On the contrary, the outflow of blood from the veins of the head, previously facilitated by the action of gravity under ground conditions, turns out to be significantly hindered under conditions of weightlessness. This causes an increase in blood volume in the vessels of the head, swelling of the soft tissues of the face, as well as a feeling of distention in the head, in some cases, a headache in the first days of flight (the so-called period of acute adaptation). In response to these disorders, reflexes arise that change the tone of the vessels of the brain.
Redistribution of blood in the vascular bed, a change in venous return, the disappearance of such an essential factor as hydrostatic pressure, a decrease in the total energy consumption of the body - all this affects the work of the heart. In conditions of weightlessness, the ratio of the load on the left and right parts of the heart changes. This is reflected in a number of objective indicators of changes in the phase structure of the cardiac cycle, bioelectrical activity of the myocardium, diastolic blood filling of the cardiac cavities, as well as in the tolerance of functional tests. Due to the redistribution of blood in the vascular bed, the center of gravity of the body shifts in the cranial direction. In the early period of being in zero gravity, a significant redistribution of blood in the vascular bed and a change in the blood filling of the heart cavities are perceived by the afferent systems of the body as information about an increase in the volume of circulating blood and cause reflexes aimed at discharging fluid.
Changes in water and electrolyte metabolism in the early period of weightlessness are explained mainly by a decrease in the secretion of ADH and renin, and then aldosterone, as well as an increase in renal blood flow, an increase in glomerular filtration, and a decrease in tubular reabsorption.
In experiments on animals, it was noted that under conditions simulating weightlessness, the value of the so-called lean lean body mass and water content in the body decrease, the sodium content in the muscles increases and the potassium content decreases, which is possibly a consequence of changes in microcirculation.
In zero gravity, the load on the spine disappears, the pressure on the interpositions ceases.
Part I. GENERAL NOSOLOGY
cartilage, the static efforts of anti-gravity muscles become unnecessary, countering the forces of gravity and allowing the Earth to maintain the position of the body in space, the general tone of skeletal muscles decreases, the efforts to move both one's own body and objects that have lost weight become unnecessary, the coordination of movements changes, the nature of many stereotypical motor acts in ground conditions. The astronaut successfully adapts to the new conditions of muscular activity in zero gravity. He is developing new motor skills. During space flights, carefully designed preventive training is carried out using bicycle ergometers, exercises on a treadmill, etc. In the absence of these preventive measures, prolonged weightlessness can cause changes in the structure and function of the musculoskeletal system.
As you know, bone tissue is characterized by high plasticity and sensitivity to re-regulatory influences and changes in loads. Mechanical stress is one of the factors affecting bone structure. With compression and tension of the bone, a negative electrical potential arises in its structure, stimulating the process of bone formation. With a decrease in the load on the bones, the genesis of the resulting disorders is associated not only with local changes, but also depends on generalized disorders of metabolic and regulatory processes. In the absence of load on the bones of the skeleton, there is a decrease in the mineral saturation of the bone tissue, the release of calcium from the bones, generalized changes in protein, phosphorus and calcium metabolism, etc. With a change in the state of bone tissue and a decrease in its mineral saturation under conditions of weightlessness and hypokinesia, the total loss of calcium is associated ... A long-term decrease in the load on skeletal muscles (in case of insufficient preventive measures) causes atrophic processes, and also affects energy exchange, the general level of metabolic processes and the state of regulatory systems, including the tone of the higher autonomic centers of the brain. It is known that muscle relaxation is accompanied by a decrease in the tone of the vegetative processes of the hypothalamus. Under the influence of weightlessness, tissue oxygen consumption decreases,
in muscles, the activity of enzymes of the Krebs cycle and the conjugation of oxidative phosphorylation processes decrease, the content of glycolysis products increases.
Stress effects. In space flight, a person is exposed to stresses (see Section 3.2.1), which are based on a combination of a number of influences, in particular, abrupt changes in the influence of gravitational forces, namely: transitions from Earth's gravity to hypergravity in the initial period of space flight in connection with accelerations during takeoff of the ship, the transition from hypergravity to zero gravity during orbital flight and return again through hypergravity to Earth's gravity at the end of the flight. Stresses caused by abrupt changes in the influence of gravity (mainly being in conditions of zero gravity) are combined with stresses caused by emotional stress, tension of attention, intense exertion, etc.
The stressors also include factors that cause space motion sickness. The cosmic form of motion sickness, which has a certain resemblance to seasickness, manifests itself in some astronauts during the first days of the flight. In zero gravity, with rapid head movements, symptoms of discomfort, dizziness, pallor of the skin, salivation, cold sweat, changes in the heart rate, nausea, vomiting, and changes in the state of the central nervous system are observed. Of the many causes of motion sickness, the first place is given to changes in hemodynamics, including microcirculation in the vessels of the brain.
According to modern data, in the genesis of the space form of motion sickness, a significant role is played by the partial loss and mismatch of information coming from various analyzer systems that provide spatial orientation, including the mismatch of information from various structures of the vestibular apparatus (under zero gravity, the function of the semicircular canals that respond to angular acceleration during rapid head movements, and the function of otoliths drops out) and inconsistency with current (unusual in zero gravity) information
Chapter 2 / DISEASE FACTORS OF THE EXTERNAL ENVIRONMENT
stereotypes stored in the long-term memory of the central nervous system at the level of the cortex and subcortical structures of the brain.
In most cases, astronauts relatively quickly adapt to the factors causing motion sickness, and its manifestations disappear after the first three days of the flight. In the early stages of flight, changes in the state of sensory systems can be accompanied by disturbances in spatial orientation, illusory sensations of an inverted body position, and difficulties in coordinating movement.
Starting from early childhood, many structures of the central nervous system participate in the formation and implementation of programs of voluntary locomotor acts, including the cerebral cortex, limbic and striatal systems, reticular formation of the midbrain, cerebellum, etc. Long-term memory provides storage in the structures of the brain the brain, including the limbic system, programs of coordinated movements. During the period of acute adaptation to weightlessness during motor acts, there is a mismatch of the altered afferentation with the programs stored in long-term memory. This creates conflict situations, and the need for an urgent restructuring of programs requires the tension of compensatory mechanisms and is one of the links in the process of adaptation to weightlessness.
In general, the period of acute adaptation to weightlessness can be characterized as a stress reaction to a combined complex of specific (zero gravity) and nonspecific (emotional stress in conditions of high motivation, intense loads, altered circadian rhythms) factors, aggravated by changes in regional blood circulation, especially in the vessels heads.
After space flights, a decrease in erythrocyte mass is noted. Recovery of hematological parameters occurs within 1.5 months after the completion of the flight. These shifts are explained by a compensatory decrease in the volume of circulating blood during flights and a much faster recovery of blood plasma volume than the mass of erythrocytes after flights. In addition, these changes in weightlessness are presumably associated with a decrease in lean body mass and compensatory response.
tions aimed at increasing the oxygen demand of tissues.
Space flight factors influence the immunological reactivity of the organism. After space flights exceeding 30 days, as a rule, there is a decrease in the functional activity of cell populations belonging to the T-system of immunity, and in some cases there are signs of sensitization to allergens of microbial and chemical nature. These changes, apparently, can be considered as a consequence of the restructuring of the immune system in the process of adaptation to a complex of flight factors, including weightlessness, additional stresses, and stay in a pressurized volume with an artificial climate. These changes increase the risk of infectious and allergic diseases. Thus, being in zero gravity conditions causes a restructuring of the functional state of the organism at various levels of its organization.
The course of adaptation processes is clearly traced in ground-based studies that simulate the influence of space flight factors on the body. Under conditions of strict bed rest (hypokinesia) in an antiorthostatic position, in which the head end of the bed is lowered at an angle of - 4 ° to the horizontal plane, changes are observed that are similar to those occurring in zero gravity. Moreover, these changes in the conditions of ground modeling in the absence of preventive measures can be even more pronounced than in space flights. They are manifested in the form of: 1) changes in systemic hemodynamics, a decrease in the load on the myocardium, detachment of the cardiovascular system, in particular, venomotor reflexes, deterioration in the tolerance of orthostatic tests; 2) changes in regional blood circulation, especially in the basins of the carotid and vertebral arteries, due to the difficulties of venous outflow from the vessels of the head and the corresponding mainly compensatory changes in the regulation of vascular tone; 3) changes in the volume of circulating blood and a decrease in erythrocyte mass; 4) changes in water-electrolyte metabolism, expressed, in particular, in the phenomena of potassium loss; 5) changes in the state of the central nervous system and vegetative-vascular shifts, the phenomena of vegetative dysfunction
Part I. GENERAL NOSOLOGY
ktsii and asthenization; 6) partial atrophy of muscles and neuromuscular disorders, expressed in a decrease in muscle elasticity, a decrease in electrical excitability and performance indicators; 7) imbalance of regulatory systems.
Under the conditions of antiorthostatic hypokinesia, the stages of adaptation processes are traced. On the example of blood circulation, it can be seen that adaptation is most quickly and completely carried out at the level of systemic hemodynamics, it is less active at the level of regional blood circulation, in particular in the basin of the carotid arteries, and even more inhibited at the level of microcirculation.
Under conditions of antiorthostatic hypokinesia, microcirculation changes. For example, in the vessels of the bulboconjunctiva of the eye, the number of perfused capillaries decreases, the ratio of the diameter of arterioles and venules changes; congestion is observed in the vessels of the fundus. In contrast to systemic hemodynamics, compensatory changes in the micro-air circulation system begin to be traced in the relatively late periods of hypokinesia.
Under the influence of hypokinesia, the predisposition to the occurrence of emotional stresses and the severity of their autonomic (cardiac and vascular) manifestations with cardiac arrhythmias and hypertensive reactions increase significantly. In space flights, the occurrence of these changes can be prevented with the help of a system of preventive measures. At the same time, with a decrease in requirements for the health of astronauts or attention to the implementation of preventive measures, the risk factor clearly increases.
Re-adaptation. At the end of the flight, the transition from zero gravity to g-forces during descent and the return to Earth's gravity from the moment of landing are combined with significant emotional stress and are, in essence, a combined stress that occurs under conditions of tense adaptation reactions. At the same time, changes in the state of the body reflect the dynamics of adaptive and stress reactions.
During the period of readaptation, the action of factors that caused dehydration in zero gravity, redistribution of blood in the vascular bed, etc., ceases. At the same time, there is a need for urgent mobilization of adaptive
"lava 2 / DISEASED FACTORS OF EXTERNAL C
mechanisms that ensure the normal functioning of the body in the conditions of earth's gravity. In the near future after the completion of the flight, some detraining of the cardiovascular system, residual disturbances of microcirculation in the vessels of the head, changes in the reactivity of the body and the state of its regulatory systems appear. The circulation quickly adapts to Earth's gravity. In particular, after many months of flights, congestion in the fundus area and signs of peripapillary retinal edema disappear within the first week after the end of the flight.
After space flights lasting up to 14 days, an increase in the activity of the hypothalamic-pituitary and sympatho-adrenal systems was noted. After flights lasting from 2 to 7 months, an increase in the activity of the sympathoadrenal system was found in the absence of signs of an increase in the activity of the hypothalamic-pituitary system. So, after many months of flights, an increase in the secretion of adrenaline (maximum on the first day) and norepinephrine (maximum on days 4-5 after landing) is characteristic with a constant concentration of ACTH, TSH, STH, cyclic nucleotides in the blood and a reduced concentration of prostaglandins of the pressor group. and plasma renin activity during these periods. The ratios of hormonal and mediator metabolism are one of the indicators of some imbalance in the body's regulatory systems.
In connection with a decrease in orthostatic stability and a changed stereotype of motor acts, it is difficult for astronauts to remain in an upright position and move without assistance during the first hours after landing. As a result of adaptive restructuring, the stereotype of motor acts is quickly restored, metabolic processes, the state of the regulatory and executive systems of the body are normalized.
The problems developed by modern space medicine cover a wide range of issues, including the elucidation of the mechanisms of human adaptation to the action of flight factors in zero gravity, the mechanisms of readaptation when returning to the conditions of earth's gravity, and the improvement of the efficiency of control of these processes.
When flying into outer space, living organisms encounter a number of conditions and factors that are sharply different in their properties from the conditions and factors of the Earth's biosphere. Space flight factors that can affect living organisms are divided into three groups.
Space travelers - dogs Ugolok and Veterok.
The first includes factors related to the dynamics of the spacecraft flight: overload, vibration, noise, weightlessness. The study of their effect on living organisms is an important task of space biology. The biological significance of weightlessness is especially great. The entire evolution of terrestrial life, biological processes took place under conditions of constant influence of the gravitational field of our planet on its inhabitants. It continues under these conditions even now. There is still no clear answer to the question of how these biological processes will proceed under prolonged weightlessness, starting with elementary - protein synthesis, cell division, enzyme action, etc. - and ending with the most complex physiological reactions. The flight of A. G. Nikolaev and V. I. Sevastyanov for 18 days aboard the Soyuz spacecraft and the unprecedented flight of G. T. Dobrovolsky, V. N. Volkov and V. I. Patsaev on the world's first orbital station " Salute "testifies to the ability of the human body to maintain high efficiency for a long time in weightless conditions.
No less difficult is the problem of inverse adaptability (readaptation) of the organism to gravity after a long stay in a state of weightlessness. It is still completely unclear whether a very long stay in a state of weightlessness (for example, when flying around Mars or Venus) will have such a harmful effect on the organism that the return of this organism to the conditions of a normal (terrestrial) gravitational field will be an excessive load for it. The design of future spaceships depends on the solution of this issue. It may be necessary to artificially create the force of gravity on them.
The second group includes factors of outer space. Outer space is characterized by many features and properties that are incompatible with the requirements of terrestrial organisms to environmental conditions. First of all, this is the almost complete absence of gases that make up the atmosphere, including molecular oxygen, high intensity of ultraviolet and infrared radiation, blinding brightness of the visible light of the Sun, destructive doses of ionizing (penetrating) radiation (cosmic rays and gamma quanta, X-rays, etc. etc.), the uniqueness of the thermal regime in space, etc. Space biology studies the influence of all these factors, their complex effect on living organisms and methods of protection against them. The third group includes factors associated with the isolation of organisms in the artificial environment of a spacecraft. A flight into outer space is inevitably associated with a more or less prolonged isolation of organisms in relatively small pressurized cabins of spacecraft. The limited space and freedom of movement, the monotony and monotony of the environment, the absence of many stimuli habitual for life on Earth create very special conditions. Therefore, special studies of the physiology of higher nervous activity, the resistance of highly organized beings, including humans, to prolonged isolation, and the preservation of working capacity under these conditions are necessary.
NASA shared preliminary results experience on the impact of space flights on the human body... The study is interesting in that two astronauts took part in it - the kelly twins... Scientists collected data on the condition of the brothers before, during and after the mission to the ISS. While Scott was in orbit for almost a year, Mark remained on Earth, and his indicators were taken as a basis.
About what puzzled the researchers the most, and whether the flu vaccine is effective in Earth orbit, - in the material RT.
Scott and Mark Kelly globallookpress.com Mark Sowa / ZUMAPRESS.com
Comparing the state of the body of the twins who flew and did not fly into space, the researchers used almost all available methods - from blood and saliva analysis to DNA sequencing. It was in it that the main differences were found.
First, the Kelly brothers showed a difference in DNA modifications. These small chemical changes (methylation) are normal and occur under the influence of the environment and stress.
As the researchers noted, the methylation process slowed down for Scott Kelly, who spent almost a year on the ISS in the company of Russian cosmonaut Mikhail Kornienko (the crew returned to Earth on March 2, 2016), but Mark Kelly, on the contrary, accelerated. After Scott returned to Earth, DNA methylation rates returned to normal, and, curiously, both.
The second and most intriguing result in the study of genomes was the elongation of telomeres. Telomeres are regions located at the ends of chromosomes. They are often associated with the aging process. It is believed likely that the longer the telomeres, the more potential a person has for longevity.
Thanks to a special protein, telomerase, telomeres can lengthen - which is what happened to Scott in space. This process was not found in Mark. However, upon Scott's return to Earth, his telomeres began to shorten again.
The reasons for the growth of telomeres in space are not yet clear, according to radiation biologist Susan Bailey of the University of Colorado, however, it is believed that this is due to increased workload and reduced calorie intake during the mission.
As for the revealed physiological changes due to being in zero gravity, they were more or less predictable. Psychiatry professor Matthias Basner from the University of Pennsylvania, who studies the effect of the flight to the ISS on cognitive functions, said that after the mission, Scott's accuracy and reaction speed decreased. Fortunately, the difference was not significant compared to previously observed similar changes during the six-month missions.
In addition, for the second part of the mission, Scott Kelly noted a slowdown in the process of restoration of bone substance and the production of a hormone that is involved in endocrine regulation and is responsible for tissue growth. Mark had no such changes.
Scott Kelly on NASA ISS
Predictable results include evaluating the effectiveness of the influenza vaccine. In space and on Earth, no differences were found. The vaccine, judging by the analyzes, is equally effective.
It is too early to talk about the final conclusions from the study: scientists have shared only preliminary data. Now they have a long analysis and search for the causes of the changes noted. One of the difficult tasks for them will be to determine which differences have appeared under the influence of an environment unusual for the body.
It is possible that a significant portion of the results will be related to the stressful situation during the mission. NASA previously reported that the final results report could be published towards the end of 2017 or 2018. The most notable discoveries, perhaps, will become known earlier.
The experiment is notable in that since identical twins are very close genetically, the difference in test results will be less related to the characteristics of the organism than between random people or other relatives. In addition, the brothers chose the same occupation and lived similar lifestyles. Mark Kelly spent 54 days in space. Scott's experience is more fundamental - a total of 520 days in space.
Influence of long-term space flight on the human body - page №1 / 1
EFFECTS OF LONG SPACE FLIGHTON THE HUMAN ORGANISM
(Some results of biomedical researchin connection with the flight of the Soyuz-9 spacecraft)
Corresponding Member of the USSR Academy of Sciences
O. G. GAZENKO,
Candidate of Medical Sciences
B. S. ALYAKRINSKY
In practice, space exploration at the present time is, first of all, the lengthening of both orbital and interplanetary flights, and, consequently, an inevitable increase in the duration of a person's stay in unusual conditions of existence. It is quite obvious that the result of the impact on the human body of all the factors of space flight, and above all the most significant ones, such as weightlessness, an increased level of radiation, afferentation changed in composition and quantity, will directly depend on the duration of these periods, which in many respects differs from the "earthly" one. a system of time sensors (stimuli that regulate the circadian rhythms of all body functions). However, very little is known about the specific features of this dependence. Science has extremely scant data in this respect. Meanwhile, the question of how long a person can stay in space without prejudice to health and performance is one of the most urgent in modern astronautics. That is why so much attention is drawn to the flight of the Soviet spacecraft Soyuz-9 with two cosmonauts on board who were in space for 18 days, that is, 4 days more than the American cosmonauts F. Bormann and D. Lovell, the former holders of the world record for the duration of an orbital flight.
Already during the planning and practical preparation of the Soyuz-9 flight, it was envisaged to obtain, as a result of biomedical observations and research, data different from those that had been delivered by previous flights of both Soviet and American cosmonauts. The reality did not disappoint these expectations, which was largely due to the great completeness and systematic character of the medical examination of the cosmonauts before, during and after the flight, and most importantly, the length of stay of A. G. Nikolaev and V. I. Sevastyanov in orbit.
The flight of the Soyuz-9 spacecraft went exactly according to the program. The microclimate parameters in its living compartments fluctuated within the stipulated limits: total pressure - 732-890 mm rt. Art., partial pressure of oxygen-157-285, carbon dioxide 1.3-10.7 mm rt. Art., relative humidity - 50-75%, air temperature - from 17 to 28 ° С.The astronauts ate canned food from natural products 4 times a day, the calorie content of the daily diet averaged 2700 kcal The drinking regimen provided for each astronaut to consume about 2 liters of liquid per day (including metabolic water). Twice during the day, the cosmonauts performed a set of physical exercises specially designed for flight.
Due to the precession of the orbit and the need to land the spacecraft during the daytime, the astronauts' sleep and wake schedule was significantly different from the usual one. At the first stage of the flight, they lie
41
go to sleep per hour. in the morning Moscow time, and then the onset of sleep gradually shifted to earlier hours, approaching midnight. Thus, a variant of the so-called migrating day with an initial 9-hour phase shift was used on board the Soyuz-9 spacecraft.
During the flight, with the help of special on-board medical control equipment, the data of registration of electrocardiograms, seismocardiograms and pneumograms of astronauts were systematically transmitted to the Earth both at rest and during functional tests and work operations. In order of mutual control, the cosmonauts measured each other's blood pressure. The "Vertical" installation was used to study the ability to spatial orientation. According to a pre-compiled program, the cosmonauts reported their health. Radio communications and television surveillance data supplemented these messages.
The flight of the ship took place in a favorable radiation environment.
Prelaunch period and flight period. The approach of the start time was accompanied in both cosmonauts by a natural increase in heart rate and respiration for such a situation. If on the eve of the start the maximum heart rate for A.G. Nikolaev was 90, and for V.I. Sevastyanov 84 beats / min, then during the hourly readiness it reached 114 and 96, respectively beats / min. A similar reaction was noted in relation to respiration: on the eve of the start, the maximum respiration rate for A. G. Nikolaev was 15, for V. I. Sevastyanov - 18, and during the hourly readiness it increased for both to 24 per minute.
In the active phase of the flight, the cosmonauts' pulse and respiration rates were at the level of the prelaunch period.
After the spacecraft entered orbit on the 6th flight orbit, the heart rate approached the one registered a month before the launch and accepted as the background one. In the future, the pulse rate continued to fall. By the 3rd day of the flight, it decreased in relation to the background in A.G. Nikolaev by 8-10, in V.I. Sevastyanov by 13 beats / min and kept at this level for about 10 days, after which it began to gradually increase and in the last third of the flight did not differ statistically significantly from the background indicators. During spinning of the spacecraft, correction of its orbit, orientation, as well as during physical exercises and some experiments, a pronounced increase in heart rate was observed in both crew members. So, on the 33rd orbit, when flight engineer V.I.Sevastyanov, performing an experiment on astro-orientation, took control of the ship, its pulse rate increased to 110 beats / min.
Respiration rate throughout the flight did not differ statistically significantly from that recorded in background studies (A.D. Egorov et al.).
As the spacecraft entered orbit, both crew members had a feeling of blood rush to the head, accompanied by the appearance of puffiness and reddening of the skin of the face. On the second day of the flight, this sensation decreased significantly, but was further exacerbated by fixing attention on it. The severity of the sensation was noticeably reduced when the spacecraft was spinning, when the astronauts were positioned along the centripetal force vector with their heads towards the center of rotation.
The sensory-motor coordination of the cosmonauts was somewhat disturbed during 3-4 days of the flight, which found its expression in some disproportion and inaccuracy of movements. On the 4th day, the movements began to acquire their characteristic clarity.
42 O. G. GAZENKO, B. S. ALYAKRINSKY
The process of orientation in space was difficult during the entire period of weightlessness both for A. G. Nikolaev and V. I. Sevastyanov. This was expressed in the fact that when floating freely with their eyes closed, they quickly lost the idea of the position of their bodies in relation to the coordinates of the cockpit. Determining the vertical direction with eyes open and closed using the "Vertical" installation, the cosmonauts in each study made more significant errors than before the flight.
Analysis of daily urine collected on the 1st, 2nd and 18th days of the flight showed an increase in the excretion of potassium, calcium, sulfur, phosphorus and nitrogen. The amount of oxycorticosteroids in the first two portions of urine was reduced, in the third - it approached the background level (G.I. Kozyrevskaya and others).
The data of radio communications, messages transmitted from the spacecraft, and television observation indicate that throughout the flight the behavior of the astronauts fully corresponded to their individual psychological characteristics and specific situations.
Starting from the 12-13th day of the flight, fatigue appeared after performing complex experiments and a busy day at work.
According to the astronauts, their appetite during the flight was normal, the feeling of thirst was somewhat reduced, sleep was mostly deep, refreshing, lasting 7-9 hours.
Post-flight period. At the initial medical examination after the flight, the astronauts looked tired, their faces were puffy, and their skin was pale. Maintaining an upright posture required a certain amount of effort, so they preferred a recumbent position. Their leading sensation at this time was the apparent increase in the weight of the head and the whole body. This sensation in intensity was approximately equal to that which occurs with an overload of 2.0-2.5 units. The objects with which they had to manipulate seemed extremely heavy. This peculiar illusion of weight gain, gradually weakening, persisted for about 3 days.
The cosmonauts underwent a shortened (5-minute) orthostatic test carried out at that time with marked stress.
A. G. Nikolaev's weight was reduced by 2.7 kg, and V. I. Sevastyanov's - by 4.0 kg.
On the 2nd day after the flight, during stabilographic examination, a significant increase in the amplitude of oscillations of the general center of gravity of the body in both cosmonauts was noted. The muscle tone of the lower extremities was decreased, the knee reflex increased sharply. A.G. Nikolaev's body strength decreased by 40 kg, V.I.Sevastyanov - by 65 kg. The perimeters of the lower leg and thigh have decreased in both.
The restoration of orthostatic stability lasted about 10 days after the flight.
Determination of the density of some parts of the skeleton of the astronauts using X-ray photometric and ultrasonic methods showed that it decreased, especially significantly in the lower extremities. This decrease on the 2nd day after the flight reached 8.5 - 9.6% in the calcaneus, and only 4.26-5.56% in the main phalanges of the fingers (E.N.Biryukov, I.G. Krasnykh ).
On the 22nd day of the post-flight period, the optical density of the bones had not yet reached the initial level.
In the study of the auto microflora of the skin and nasal mucosa, a pronounced dysbiosis was noted. Dysbacteriotic shifts
INFLUENCE OF SPACE FLIGHT ON THE ORGANISM
basically boiled down to the appearance on the smooth skin and nasal mucosa of astronauts of a large number of gram-positive non-spore-bearing rods, which were not detected before the flight, which apparently gives grounds to class them as representatives of the "alien flora" (VN Zaloguev).
Medical observation materials obtained during the flight of the Soyuz-9 spacecraft and in the post-flight period testify to the fundamental possibility of man's existence in space for 18 days while maintaining sufficient mental and physical working capacity. At the same time, this material leads to the conclusion that, in general, the cycle of "adaptation-readaptation" in space-Earth conditions requires a prolonged tension of the organism's adaptive mechanisms and that readaptation to the usual living conditions is a more difficult process.
The development of tools and methods to facilitate this process is an important task of space medicine. For its successful solution, it is necessary with sufficient completeness to find out the specific value of each factor of space flight in the influence that their complex has on the human body. The study of the mechanisms of the body's responses to each of these factors is also of no less importance. Progress in this direction can only be ensured through the accumulation of a large amount of factual material.
From this point of view, the significance of the 18-day flight of Soviet cosmonauts can hardly be exaggerated. It is undoubtedly a major step in solving the problem of the differential significance of space flight conditions, of their share in changing the physiological functions of astronauts in orbit and after returning to Earth.
What conditions on board Soyuz-9 were responsible for these changes?
Radiation can be eliminated from these conditions immediately. Indeed, the total radiation dose received by each astronaut was well below the permissible level.
The role of neuro-emotional stress in the general response of the astronauts to the flight also, apparently, was comparatively insignificant. In any case, the content of oxycorticosteroids in their urine turned out to be reduced in relation to the conditional norm, although it is known that any neuro-emotional stress is accompanied by an increase in the amount of these substances in the blood and urine. So, in persons (non-pilots) who made a 50-minute flight in the airfield area, the level of steroid hormones increased by 40-50% compared with the pre-flight indicators (H. Hale, 1959). In professional pilots, after short-term, but very difficult flights on well-mastered jet aircraft, the amount of 17-OH-corticosteroids in the urine during the first two to three hours after the flight increases by 50-60% (IV Fedorov, 1963).
These and many other data suggest that the neuro-emotional stress of the Soyuz-9 crew members was not in any way significant, at least on the 1st, 2nd and 18th days. And since just on these days one should expect the most intense emotional reaction in cosmonauts, which is natural at the start and finish, emotiogenic factors cannot be considered an essential reason for the changes in physiological functions noted in them.
In all likelihood, the severity of the experiences of A.G. Nikolaev and V.I.Sevastyanov was reduced in connection with a successful, uncomplicated
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O. G. GAZENKO, B. S. ALYAKRINSKY
the fulfillment of the flight program, favorable radiation conditions, uninterrupted radio and television communications during the hours of the scheduled sessions, good preliminary training of both crew members, as well as the fact that one of the cosmonauts had already flown and his confidence in the successful completion of the flight was transmitted to his partner.
It is rather difficult, if not impossible, to assess the significance of the disturbance in the "afferent supply" of the cosmonauts' organism during the Soyuz-9 flight with sufficient completeness and reliability. However, some considerations in this regard deserve attention.
In experiments on the study of the so-called sensory insufficiency, carried out in terrestrial conditions, it was shown that the impoverishment of the general afferent flow does not pass without a trace for a person. Its first and main result is various disorders in the mental sphere, which are most pronounced in cases of the most complete exclusion of visual, auditory, tactile, kinesthetic and other sensations. In such experiments, the subjects were registered various changes in consciousness, up to hallucinations. The main difference of these experiments from the conditions of space flights is the impossibility to exclude on the Earth the afferentation coming from gravireceptors, while in space it weakens and, apparently, changes.
During the entire flight, neither A. G. Nikolaev, nor V. I. Sevastyanov had a single case of mental disorders. Their behavior in the broadest sense of the word, the quality of work and research operations, their speech and content of transmitted information, entries in the logbook, etc. indicate that the cosmonauts did not experience states of sensory deprivation, at least in the form which is typical for ground-based experiments. The influence of afferentation, altered in composition and quantity (first of all, proprioceptive and tactile, as well as, to some extent, vestibular, visual and auditory) on the psyche of astronauts was either very insignificant or well controlled.
Thus, neither radiation, nor neuro-emotional stress, nor sensory insufficiency can be considered as significant causes of changes in physiological functions. There is every reason to classify weightlessness as the most important causes of these shifts, as well as the unusual rhythm of sleep and wakefulness of the Soyuz-9 crew members.
The problem of weightlessness continues to be the arena of fierce discussions between representatives of different points of view. While some researchers do not attach any serious importance to weightlessness (L. Mallon, 1956; I. Walrath, 1959), others believe that it is a formidable damaging factor and that the existence of terrestrial organisms in weightlessness is impossible. Moreover, there is an opinion that even a long-term change in the direction of the force of gravity with a low value of weight can be fatal for the body (V. Ya. Brovar, 1960).
Based on the data of comparative physiology, even the following conclusion is formulated: the evolution of animals is essentially the evolution of adaptations aimed at overcoming the forces of gravity, which was associated with increased expenditure of energy, for the release of which a significant amount of oxygen, and hence hemoglobin, is required. From this point of view, in zero gravity, the erythropoietic function will gradually decrease, as a result of which progressive atrophy of the bone marrow will begin (PA Korzhuev, 1968).
Numerous works of domestic and foreign authors emphasize the negative influence of weightlessness not only on the function of the bone
INFLUENCE OF SPACE FLIGHT ON THE ORGANISM
brain, but in fact on all systems of the body, on the body as a whole. "Vulnerability" is especially noted in conditions of weightlessness of the cardiovascular and musculoskeletal systems.
Experiments carried out in pools and elevators, during the flight of specially equipped aircraft along the ballistic curve, data obtained in orbital flights, and theoretical developments make it possible with a high degree of probability to attribute the following phenomena to the results of the impact on the human body of weightlessness: various disturbances in spatial orientation, some types of so-called vestibular illusions, in particular oculogyral, changes in the temporal-spatial-power structure of motor skills, hemodynamic shifts (one of the symptoms of which is hyperemia and puffiness of the face associated with increased blood flow to the head), decreased physical strength and atrophic phenomena in muscle tissues and decalcification of the skeleton.
When returning to the Earth's gravitational field, the aftereffect of weightlessness is expressed in increased lability of the cardiovascular system, one of the manifestations of which is orthostatic instability, in violation of functional motor structures responsible for maintaining posture and locomotion, in the appearance of the illusion of an increase in the weight of one's own body and objects familiar by weight. ...
When comparing this complex, multicomponent response of the organism only to weightlessness with those reactions to flight as a whole, which were recorded by A.G. Nikolaev and V.I. the factor is weightlessness.
However, there are reasons to associate some of the reactions of astronauts noted in their orbit not only with weightlessness, but also with the peculiarity of their work and rest regime. As already noted, the cosmonauts lived according to the scheme of the so-called migrating days with an initial phase shift of about 9 hours. Now, very numerous data from special studies indicate that the mode of work and rest of a person turns out to be all the more close to optimal, the closer the routine of sleep and rest in this mode coincides with the daily rhythms of its psycho-physiological functions inherent in the human body. Numerous facts testify to the direct dependence of the well-being of the organism on these rhythms. Thus, K. Pittendray (1964) indicates that circadian rhythms are an integral property of living systems, form the basis of their organization, and that any deviation from the normal course of the rhythm leads to disturbances in the work of the whole organism. The normal course of the rhythm is supported by cyclically changing factors of the external world, which in biorhythmology are called synchronizers or time sensors. Most of them are the result of the rotation of the Earth around its own axis. In all cases of mismatch of the cycles of time sensors and rhythms of the body, the latter experiences a state of so-called desynchronosis, which in relation to a person takes the form of pronounced fatigue, overwork, or even various reactions of a neurotic type.
Desynchronosis can occur in all cases of violation of the usual system of time sensors: when rapidly crossing several time zones (transmeridional flights), when working at night, in the Arctic and Antarctic conditions, in space flights. One of the causes of desynchronosis is also the migration of the day, that is, a constant or periodic change in the onset of sleep, and hence wakefulness, in the diurnal. mode of work and rest.
4 $ O. G. GAZENKO, B. S. ALYAKRINSKY
The migrating days taken on board the Soyuz-9 spacecraft may be one of the reasons for the astronauts' fatigue, noted by them for the first time on the 12-13th flight day. There is reason to believe that the negative effect of weightlessness was intensified by periodic changes in the rhythm of sleep and wakefulness (BS Alyakrinsky).
The ranking of extreme factors in relation to the flight conditions of the Soyuz-9 spacecraft can be useful for specifying preventive measures aimed at reducing the negative influence of these factors. Since the specific value of weightlessness seems to be the greatest, the idea of artificial gravity (that is, the use of the principle of centrifugation) receives an additional argument in its favor.
Muscular atrophy, which was observed in astronauts only in relation to the lower extremities, apparently can be successfully prevented by specially selected physical exercises.
It is quite clear that the most serious attention should be paid to maintaining the daily rhythms of its functions inherent in the body during long space flights. The difficulties of adapting to unusual daily rhythms must be borne in mind already when setting up a system for selecting cosmonauts. It has been shown experimentally that people react differently to an emergency change in work and rest regime. For some, this change is extremely easy, for others, on the contrary, it is a difficult task. Reliable prevention of desynchronosis on board the spacecraft is the strict observance by astronauts of rational work and rest regimes developed on the basis of biorhythmology data.
Research into the problem of man's long-term existence in space is just beginning. This problem can be resolved only through the accumulation of more and more facts in long-term space flights, with a specially developed program of medical observations. Such flights include the flight of the Soyuz-9 spacecraft.
Man first flew into space in 1961, but even half a century later there are no exact answers to 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 greatly affect their health both during the flight and after. Many astronauts, after a certain period of time spent in zero gravity, cannot return to their previous indices 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 zero gravity the blood is distributed differently and the heart beats more slowly.
In addition, the density of bone mass decreases, due to the fact that the body is not affected by the 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 process of metabolism 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 microgravity conditions and have turned out to be extremely genetically unprepared for them.
Because of this, the immune system perceives weightlessness as a threat to the entire body as a whole and tries to activate all possible defense mechanisms at once.
In addition, in conditions of isolation from familiar conditions, the human body is faced with a minimum amount 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 activity, 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 body temperature regulation, but scientists still do not understand the mechanisms that stimulate these changes.
It turns out that space flight reduces the content of various protein groups in the human body. Some of them quickly bounce back, 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 under microgravity conditions 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 a 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.
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 whose concentration changed during their stay in space were associated with only a few body processes, such as fat metabolism, blood clotting and immunity.
