Scientists have long tried to define the concept of “life”. But this is quite difficult to do, because the organisms inhabiting the planet are very diverse. You will learn from our article what are the criteria for living systems and the features of their functioning.
What is the system
A system is a collection of elements that are connected in a certain sequence. This structure ensures their integrity and ability to function. Based on their origin, systems can be artificial or natural. The first includes all structures that man has created. Their examples are varied: from a ballpoint pen to a skyscraper. Agree, in both the first and second cases, all the components of these systems are subject to clear patterns and are combined into in a certain order. Their slightest violation can change the entire mechanism of work.
However, gravity can influence the behavior of cells and their construction in more profound and subtle ways. However, since basic research began in the space environment, it became obvious that biological properties change as gravitational force decreases, highlighting the relationship between physical strength and biological function. Adhesions of cellular substrates, as well as connections between cells, accordingly strongly influence Earth's gravity, impairing multicellular aggregates and tissue formation, while such structures are more easily tolerated for days or months in microgravity.
Living systems are all the structures that surround us, but were not created by man. They are "products" of nature. Microscopic amoeba cells, giant coniferous trees, huge blue whales - all these are living systems. These organisms actually have many elements that interact with each other in a certain way. What are the general criteria for living systems? And does this concept include protein globules or water molecules? After all, they also consist of individual elements connected in a certain sequence. Scientists state unequivocally that life is only a collection of elements enclosed in a cellular structure.
These modifications ultimately result in a significant change in the way the cell sensing apparatus responds to wide range environmental and internal biophysical stresses. Girardi et al confirmed that microgravity induces a generalized inhibition of proliferation and a contemporary increase in the rate of apoptosis. Indeed, and unfortunately, almost weightlessness sharply worsens biological functions and thus, contrary to what was previously thought, cells cannot be considered “blind” to gravity.
Levels of organization of living systems
Living systems in nature exist at different levels of organization, which differ in the structural features and interactions between their components. Molecular is also one of them, but its independent existence outside the cell is impossible. Most main process, occurring at this level is the storage and sale of genetic material. The criteria for living systems are most clearly illustrated by the example of a cell. It is precisely this that is structural and functional unit all living things. Plants, animals, fungi and bacteria are made up of cells. An exception is viruses, which are a collection of nucleic acid and protein molecules.
Cells can “sense” changes in microgravity through an indirect mechanism; development of specialized structures for mechanical perception and transduction of gravitational forces; and changes in enzyme kinetics dynamics or protein network self-assembly. It is worth noting that the last two processes are dramatically affected by nonequilibrium dynamics. Nonlinear dynamic processes far from equilibrium involve an appropriate combination of reaction and diffusion, and the pattern resulting from these interactions is strongly influenced by even minimal changes in reactant concentrations or changes in the strength of the morphogenetic field.
Next comes the complication of living systems. Cells combine to form tissues. Each of them specializes in performing a specific function. The totality of tissues represents the next level - organismic. However, in nature, individuals do not exist separately. They interact with each other and with At the same time, they consistently form the population-species, biogeocenotic and biosphere levels. The latter is the most global, uniting absolutely everyone inhabiting all habitats.
Processes of this type are called Turing or dissipative structures, given the energy consumption required to control and maintain the system away from equilibrium. This necessary condition necessary so that the system can quickly change its configuration in accordance with the needs of the system. In turn, dissipative energy provides thermodynamic driving force self-organization processes. Masiello et al. In which it is shown that a state of almost weightlessness causes systems to move towards various conditions attractors, allowing cells to acquire new and unexpected phenotypes during a true transition phase.
Features of the chemical composition
The basic properties of living systems, regardless of their level of organization, are characterized, first of all, by a certain chemical composition. These structures are based on four chemical element. These are carbon, oxygen, nitrogen and hydrogen. They are also called organogenic. They, in turn, form molecules of biopolymers - proteins, carbohydrates, lipids and nucleic acids.
According to such results, gravity appears to be an "inevitable" constraint that obliges living things to adopt only a few configurations among many others. This statement raises several important issues. Some of these entail fundamentals of theoretical biology, as they challenge the gene-based paradigm in which biological behavior can be explained solely genetic mechanisms. What is the mechanism by which microgravity can change cell function and structure so profoundly?
Metabolism
Any living organism is open system. This means that there is a continuous exchange of substances with the environment. The intake of substances, their transformation, and the removal of final metabolic products are integral features of living systems. Entering the body, complex molecules are broken down to release a certain amount of energy. It is necessary for growth and development to occur.
Levels of organization of living systems
Several studies included in this issue address this topic, calling for the question of a critical role supported by the cytoskeleton in mediating several microgravity-based effects. Disorganization of basic cellular architecture can influence activities ranging from cellular signaling and migration to the cell cycle and apoptosis. As such, they are likely to be very rapidly involved in cell adaptation to microgravity-related conditions.
Ferranti et al. Where a significant correlation was documented between cytoskeletal abnormalities induced by simulated microgravity and increased autophagy. However, changes in the cytoskeleton influence Various types cells, including endothelial cells. Cytoskeletal changes also have profound consequences for both cell shape and tissue modeling.
Self-reproduction ability
The ability to reproduce or self-reproduce and regenerate are also criteria for living systems. These properties ensure continuity at all levels, making life possible on the planet as a whole. Methods of reproduction depend on the structural features. For example, bacteria reproduce by dividing cells in two, plants - vegetatively and with the help of spores, and animals - sexually.
Self-reproduction ability
Overall, the changes that occur in microgravity are undoubtedly significant. backlashes on physiological homeostasis of the whole organism. Gravity really does have crucial for spatial perception, postural balance and motion generation.
Components that form the system
The brain can deal with the gravitational field by integrating a wide range of various signals, allowing the system to initiate the most appropriate response. The second study, in turn, showed positive effect neurophysiological adaptation to weightlessness and how knowledge acquired in this area can even contribute to the development innovative technologies gait rehabilitation. Microgravity and hypergravity research effectively advances our knowledge of physiology and biochemistry, thereby providing valuable data and models for understanding some important diseases person.
Regeneration helps many organisms maintain their viability for as long as possible. Coelenterates, worms, reptiles and plants are capable of restoring lost or damaged body parts. The cells of the freshwater hydra are dividing especially actively, the body of which can be restored from 1/200 of the part.
Moreover, space exploration has played and, apparently, will play important role in reforming theoretical basis in biology and physiology and can serve as a new paradigm for innovation. Namely, research related to microgravity has contributed to the development of new tools such as culturing cells in three dimensions. Indeed, 3D culture in real and simulated microgravity allows for a more precise assessment of the role of biophysical constraints in shaping cell phenotypes and functions.
In turn, such devices could help improve tissue engineering techniques. Such studies may indeed provide valuable information about modulations in signal transduction, cell adhesion, or the extracellular matrix caused by altered gravity conditions. These systems also facilitate the analysis of the influence of growth factors, hormones, or drugs on these tissue-like constructs to better address issues such as pharmacokinetics and pharmacodynamics.
Movement
No wonder they say that movement is life. And indeed, moving in space, animals look for food, individuals of the opposite sex or Better conditions for existence. Their unicellular representatives move with the help of organelles - flagella, pseudopodia or cilia. Surprisingly, plants are also capable of movement. Everyone watched as leaves and flowers turned towards the light, and vine shoots twined around any surface. These are growth
These tools may also allow investigation of developmental and organogenesis processes. The motivation for this issue focused Biomed Research International Journal is to review the state of research and determine possible areas for future development. There is an urgent need for this since the last comprehensive collection of studies on space biomedicine research dates back to the 90s.
As editors, we have collected an eclectic mix of articles contributed by research groups fully involved in space biomedicine research, and have been actively involved in research conducted both on the International Space Station and on the ground, with various methods, allowing the simulation conditions of weightlessness and increased gravity to be met. This is not a one-size-fits-all approach. It's more like "let the color be a hundred colors." However, they provide a fruitful overview of what will come from space biomedicine research.
Growth and development
Growth and development are integral properties of living systems. The first involves quantitative changes in organisms. Growth occurs through cell division. Moreover, in plants it is unlimited. This means that they grow throughout their lives. But animals - only up to a certain period. Growth is also accompanied by quantitative changes in the body - development. This process consists of acquiring increasingly complex features of organization and physiology. Their position in the system of the organic world depends on the level of development of organisms. Eg, angiosperms have become widespread due to progressive structural features, which include the presence of a flower and
Overall, the studies reported in this issue have demonstrated how important physical signals can be in shaping biological phenotypes and function, influencing such profound molecular and genetic pathways. In addition, research in the field of microgravity has forced us to develop new technological solutions and more suitable experimental models.
Thus, the knowledge collected in space research, have provided invaluable support to the understanding of human physiology and pathology, the advancement of technological innovation, and the development of invaluable medical and experimental devices. This is why it is stated that the ultimate cause of research outer space human being is precisely what allows us to discover ourselves. Undoubtedly, microgravity and space exploration represent an unlimited horizon for exploration and discovery.
Irritability
Another feature of living systems is their ability to respond to any changes in environment. This property is called irritability. Thus, tulip flowers open when warm, and mimosa leaves fold when touched. In animals, irritability is carried out using nervous system and manifests itself in the form of reflexes. Some of them are congenital. These include breathing, protective, grasping, sucking, and blinking reflexes. They ensure vitality from the first minutes of life. In the course of changes in existence, animals acquire new behavioral reactions.
Controlled studies conducted in microgravity can advance our knowledge by providing surprising and unanticipated insights biological mechanism, underlying physiology as well as many related diseases such as cancer.
Atoms and molecules are grouped to create cells, they are organized to create tissues and tissues grouped into organs, organs in turn form apparatuses and systems, and finally systems configure everything Living being. A group of individuals who share the same genetic characteristics constitute a population, and a group various groups population forms a community, furthermore, communities interact with their habitat to form a Biome, and the sum of all these parts gives birth.
The properties of living systems ensure their existence throughout their individual and historical development. These include cellular structure, unity chemical composition, metabolism, ability to reproduce, grow, develop, irritability and adaptation.