Homeostatic Maintenance in the Human Body

The structure and function of different systems

Constancy of the internal environment and the relative stability of physico-chemical parameters in children are provided with the expressed prevalence of anabolic over catabolic processes of exchange. This is a prerequisite for growth and sets the child’s body from the body of adults who intensity of metabolic processes in a state of dynamic equilibrium. In connection with this neuroendocrine regulation of homeostasis child’s body is more intense than in adults. Each age period is characterized by specific features of homeostasis mechanisms and their regulation. (Marieb et al. 2007)

Therefore, in children more often than adults, there are severe disturbances of homeostasis, often life-threatening. These disorders are often associated with immaturity of homeostatic functions of the kidneys, with disorders of the gastrointestinal tract or respiratory function of the lungs. (Bhagavan, 2002)

The absolute increase in extracellular fluid volume lags behind the rise of the total weight, so the relative amount of the internal environment, expressed as a percentage of body weight, decreases with age. This dependence is particularly pronounced in the first year after birth. In older children, the relative rate of change of extracellular fluid volume decrease. The regulation system constant volume of fluid provides compensation for variations in the water balance in a fairly narrow range. The high degree of hydration of tissue in infants and young children determines significantly higher than in adults, the child’s need water (per unit of body weight). Water loss or limit quickly leads to the development of dehydration due to the extracellular sector, i.e. internal environment. With kidneys – the main executive body in the system volyumoregulyatsii – do not provide water savings. (Marder and Bucher, 2001)

Negative and positive feedback mechanisms in homeostasis

The limiting factor is the regulation of renal tubular immaturity. The most important feature of the neuroendocrine control of homeostasis in infants and young children is relatively high secretion and renal excretion of aldosterone, which has a direct effect on the hydration of tissues and function of the renal tubules. Regulation of the osmotic pressure of blood plasma and extracellular fluid in children is limited. The osmolarity of the internal medium varies over a wide range (± 50 mOsm / l) than in adults (± 6 mOsm / l).

This is due to the larger quantity of body surface per 1 kg of weight and, therefore, with more significant losses of water during respiration, as well as the immaturity of the renal mechanisms of urine concentration in children. Impaired homeostasis manifested giperosmosom especially common in neonates and children first months’ life in older age begins to dominate gipoosmos associated mainly with gastrointestinal disease or kidney disease. Less studied ion regulation of homeostasis, which is closely connected with the activity of the kidneys and the nature of power. Previously it was thought that the main factor determining the magnitude of the osmotic pressure of the extracellular fluid sodium concentration is, however, more recent studies have shown that a strong correlation between the content of sodium in the blood plasma and the magnitude total osmotic pressure in the pathology exists. (Leon and Russell, 2004)

An exception is plasma hypertension. Consequently, holding homeostatic therapy by introducing glucose level solutions requires not only control over the content of sodium in serum or plasma, but also changes the total osmolarity of the extracellular fluid. Of great importance in the maintenance of the total osmotic pressure in the internal environment is the concentration of sugar and urea. (Bucher et al. 2003)

Exchange of gases

The contents of these osmotically active substances and their effect on the water-salt metabolism in many pathological conditions may rise sharply. Therefore, for any violations of homeostasis is necessary to determine the concentration of sugar and urea. By virtue of the foregoing, in young children in violation of water-salt and protein modes can develop latent state of hyper – or gipoosmosa, hyperasotemia. (Postolache, 2005)

Important indicator of homeostasis in children is the concentration of hydrogen ions in the blood and extracellular fluid. In the antenatal and early postnatal periods, regulation of acid-base balance is closely related to the degree of blood oxygen saturation, which is explained by the relative predominance of anaerobic glycolysis in bioenergetic processes. However, even moderate hypoxia in the fetus is accompanied by accumulation in its tissues of lactic acid. Furthermore, immaturity atsidogeneticheskoy renal function creates the preconditions for the development of “physiological” acidosis (shift of acid-base balance in the body in the direction of the relative increase in the amount of acid anions. (McEwen, 2003)

Due to the nature of homeostasis in newborn disorders often arise, standing on the brink between physiological and pathological. Restructuring of the neuroendocrine system during adolescence (puberty) is also associated with changes in homeostasis. However, the functions of the executive organs (kidneys, lungs) reach in this age of maximum ripeness so severe disease syndromes or homeostasis are rare, but more often it is a compensated shifts in metabolism that can be found only with the biochemical study of blood. (Moal, 2007)

The clinic for homeostasis parameters in children is necessary to investigate the following parameters: hematocrit, total osmotic pressure, the content of sodium, potassium, glucose, bicarbonate, and urea in the blood, and blood pH, p02 and pCO2. (Bucher et al. 2003)

Oxygen transportation in the human body

One and the same level of homeostatic variables at different ages is supported by various shifts in their regulatory systems. For example, the persistence of blood pressure at a young age is supported by a higher cardiac output and low total peripheral vascular resistance, and in elderly and senile – due to higher total peripheral resistance and reduce the amount of cardiac output. Constancy during aging the most important physiological functions is supported in terms of reliability and reduces the reduction of the possible range of physiological changes homeostasis. (Goldstein, 2007)

Retention of homeostasis in essential structural, functional and metabolic changes achieved by the fact that at the same time is not only fading, disturbance and degradation, but also the development of specific adaptive mechanisms. Essential in maintaining homeostasis in the process of aging are changing mechanisms of neurohumoral regulation, increasing tissue sensitivity to the action of hormones and neurotransmitters on the background weakening of nervous influence. (Büschges et al. 2004)

During aging varies considerably heart function, pulmonary ventilation, gas exchange, renal function, secretion of digestive glands, the function of the endocrine glands, metabolism, etc. These changes can be characterized as gomeorezis – regular trajectory (dynamic) changes in the metabolic rate and physiological functions of age in time. Progress value age-related changes are very important to characterize the process of human aging, to determine its biological age. (Goldstein, 2007)

In elderly and senile age reduces overall potential adaptive mechanisms. Such a decrease in reliability mechanisms of homeostasis is one of the most important prerequisites for the development of pathological disorders in old age. Thus, homeostasis – is an integral concept of functionally and morphologically combines cardiovascular system, respiratory system, renal system, water and electrolyte metabolism, acid-base balance. The amount of blood ejected by the heart in 1 min., Is the minute volume. However, the function of the cardiovascular system is not simply to maintain a given cardiac output and its distribution in the basin and changes in cardiac output in accordance with the dynamic needs of tissues in different situations. (Wyatt et al. 1999)

Nutrient transportation in the human body

Many surgical patients experience a sharp fall in cardiac output, which disrupts the delivery of oxygen to the tissues and can cause cell death, the body and even the whole body. Therefore, the assessment of the cardiovascular system should be taken into account only to the minute volume, but also the oxygen supply and the need for it. The normal function of the respiratory system – is to maintain a constant level of oxygen and carbon dioxide in arterial blood in normal vascular resistance in the pulmonary circulation and normal energy expenditure on work of breathing. (Prinz et al. 2004)

This system is closely linked with other systems, and especially cardiovascular. Function of the respiratory system includes ventilation, pulmonary circulation, and diffusion of gases through the alveolar-capillary membrane, transport of gases in blood and tissue respiration. Functions of the renal system: kidneys are the main organ, designed to preserve the constancy of physico-chemical conditions in the body. It includes: the regulation of water and electrolyte balance, maintain acid-base balance and removal from the body of metabolic products of protein and fat. (Parris, 2006)

In the literature, it was noted that the development of ideas about the physiological mechanisms of regulation of movements over a long period of time determined by the reflex theory reigned supreme organization of the control functions of the brain. In the framework of these concepts were viewed as “chain” reflexes in which one end of the motor act (or part thereof) serves as a signal to start the next act (part).

Anatomical structure of the body systems

By analogy with the laws identified in experiments with conditional reflex conditioned behavior, it is believed that repeated re-execution of certain movements of the structure leads to the development of the stereotype – a steady sequence of activation of the nerve centers that control muscle contractions, and to run the entire chain of sufficient initial “start” signal. (Bucher et al. 2005)

The term “motor stereotype” explains well learned solidly conservative movements, their stability over time, but it is quite unsuitable to adequately reflect the variability of their characteristics, plasticity and adaptability to the changing conditions of execution. This led to the appearance in the domestic literature inherently contradictory term “motor dynamic stereotype” in which the definition of dynamic used as a synonym for changeable. (Pulver et al. 2005)

In general, the above shall not affect the presentation of specific physiological mechanisms of regulation and the introduction of motion parameters proposed in this paper the concept of homeostasis motor functions can fill a number of gaps in the theory of conditioned reflex control motility. (Parris, 2006)

Task 2

It is generally accepted that a significant contribution to the presentation of the principles and mechanisms of control of movements made ​​works NA Bernstein (1935, 1947, 1961, 1966). It is no exaggeration to say that it is ideas NA Bernstein last thirty years, determined the development of the theory of kinesiology. Considering the regulation of voluntary movements of man as the task of managing a complex kinematic system first opened N.A. Bernshteyn being coordinated activity as a process of overcoming the excessive number of degrees of freedom in the joints, musculoskeletal system conversion to a managed system. (Marder and Bucher, 2005)

Based on the properties of a multilink system – control object for the nervous system, NA Bernstein formulated the requirements for it as a system of control movements. Here it is appropriate to allocate only made ​​it into the physiology of movement’s crucial concepts and ideas, such as the purpose, activity, search, hierarchical, closed loop control and sensory feedback.

Wide popularity of these concepts makes unnecessary disclosure of their contents. We note only that the greatest attention by students and followers NA Bernstein paid to the development of his ideas correctional governance at the expense of equally important concepts of programming movements. From our point of view, the concept of homeostasis motor functions not only contradicts the notion NA Bernstein, but significantly develops the least known part of his theory, as it is a programming activity of the brain is the basis of homeostasis of voluntary movements. (Parris, 2006)

Based on the concepts of circular regulating movements in individual parameters (power, spatial, temporal) Gel’fand and Tsetlin (1966) hypothesis was formulated neindividua-lysed control in complex systems, according to which the system of coordination of movements seen as having a set of relatively independent subsystems. The activities of each subsystem is constructed so that a minimum number of information coming from the external environment and from other subsystems (implement the principle of least interaction on which are the relations between the different levels of government). This hypothesis provided the impetus for the emergence of ideas about synergies – maintain upright posture, breathing and other synergies. (Marder et al. 2005)

In the study of the control functions of the brain NP Behterevoj (1966, 1967, 1971, 1974, 1980) formulated the concept of rigid and flexible links provide brain activity and minimize brain systems software. Hard links are characterized by stable and consistent reproduction. (Moal, 2007)

Apparently, the idea of ​​synergies, minimize the interaction between the levels of control of movements, rigid and flexible links functioning of brain structures are quite compatible with the concept of homeostasis of motor functions. Moreover, from our point of view, this is precisely the concept of getting a consistent explanation of many “difficult” questions for these theories. For example, from the concept of synergy can not deduce explanations organization control actions on motor neurons of the spinal cord segments that innervate the muscles together in synergy, and draw conclusions about the role of proprioceptive afferent in this process. (Parris, 2006)

Studied model organized behavior of basic elements involved in the implementation of the motor act at the spinal level, allowed to come to the conclusion that in the process of change in muscle length and it stresses arising in numerous structures proprioceptive ties ring mechanism of homeostatic regulation are management activity of motoneurons that distributes action afferent signals so that changes in the activity of motoneurons pool contributed to the reduction of increased under the influence of external disturbances of the afferent input to the central unchanging background influences. (Bucher et al. 2006)

Multiparametric autogenous regulation activity of motoneurons further enhances gomeostatiruyuschy effect because the individual ring structures take on other functions if you disable one of them, and under the joint action contribute to early achievement of motoneurons device pool to the external load in accordance with the chosen target regulation. (Moal, 2007)

Maintain homeostasis of motor function at the spinal level serves more bright manifestation, if we consider the influence of muscle afferents in the group II spindle broad convergence of different muscles which one motoneuron and divergence on different muscles of one limb shown recently (Schomburg, Steffens, 1985). Consequently, the system static and dynamic y-motoneurons should be considered in terms of the organization of a coordinated contraction of various muscle groups during the execution of the movement.

We believe that both motor neurons and interneurons segmental level are included as elements in the regulation of other rings like lockable on the spin-regional level and formed with the participation of suprasegmental structures. Each of these rings in the stationary state stabilizes the circulating flow in which the pulse modulation and the activity level of circulating streams in the associated rings of regulation. (Bucher et al. 2007)

As shown, the actual regulatory ring at the segmental level does not provide for external perturbations on locomotion maintain the desired length and muscle tension. Adhering to the principle of hierarchical organization of the brain, the authors of numerous works in the center of consideration put notions of local neural circuits (but not rings) – modules in which groups of nerve cells combined vertical links in a separate “mini-speakers” representing certain prize-Naki external signals (or images), the totality of which is incorporated in the tangential connections “macro-column”. (Moal, 2007)

Some of the properties presented in the column of the macro signal are analyzed in parallel, and the same modules may be included in different brain distributed system. In different model representations of numerous connections between brain structural formations are not considered as rings regulation, the more capable homeostated circulating pulse flows in them.

Communication process is still limited to considering only the “direct” connections from one block to another – descending or ascending, afferent or efferent pathway. In a tough (if not to affect the development processes of the body and learning) neural structure interacting rings are continuous processes of self-education and functional decay under coming to elements of the structure of signals (pulse flows), which provides the necessary structure search traffic, leading to the implementation of a specific motor act , to achieve the objective reality. (McEwen, 2003)

Multiple (leading to the formation of programs) to perform movements to perpetuate relations of interacting homeostatic regulation of the rings and their possible reuse as develop skills through the implementation of this movement long periods of time to solve the same problem. (Marder, 2007)

Despite our attempts to identify the hard muscle synergy relations at runtime programmatically implemented driven to automatism movements, what is considered locomotion , we came to the conclusion that the individualized management of each of the muscle contraction, the relationship between the anatomical agonist activity vary from synergistic to antagonistic over the implementation of elementary driving cycles. (Postolache, 2005)

We can assume that in the process of becoming the first sensorimotor skills are formed fairly stable ring structures that combine elements of sensory and motor distributed networks. Such association operating in the regulatory elements of the ring can make the structural basis of the program regulation of movements, providing homeostasis of them, keeping for each individual its characteristic “handwriting”. The interaction between the control circuits of the ring very rapidly and covers a range of transitions from completely blocking circulation pulsed flux in the ring to ignore modulating influences on impulses in the ring, if it is stabilized at large intensities. (Leon and Russell, 2004)

References