Regulatory mechanisms: what they are and how they make the organism function.

An overview of genetic, physiological and general Biological regulatory mechanisms.

Living beings, both animals and plants, are open systems that obtain nutrients and gases from the environment and excrete waste substances into our environment on a continuous basis. What for us are feces, for other microorganisms and invertebrates are succulent substances that are transformed into part of their tissues (organic matter), thus allowing the continuation of the carbon cycle within the trophic chains of ecosystems.

Being an open system is necessary for survival: energy is neither created nor destroyed, it is only transformed (according to the law of conservation of energy) and, therefore, we must continuously obtain it from the environment. However, this also has several negative points, such as that we constantly dissipate heat into the environment, we depend on our environment for all our biological tasks, and we can get sick and die as a direct consequence of what happens in our environment.

To bring some order to the ever-changing chaos that is the environment, our bodies present a series of biological and/or physiological regulation mechanisms to maintain a stable internal condition, compensate to maintain a stable internal condition, compensating for the changes that may occur in the environment. Let's see how they are.

What is a regulatory mechanism?

In biology, a mechanism is a system with parts that interact causally, giving rise to processes that have one or more effects on the environment, whether internal, external or both.. One mechanism may be the process that leads to human sweating at a hot moment (physiology), but natural selection or genetic drift are also considered mechanisms, although in this case of an evolutionary nature.

In the world of regulatory mechanisms, nothing is black and white, because biological entities are extremely complex (multicomponential) beings whose systems are in continuous interaction and feedback.. Beyond their diversity, three major levels can be distinguished in the underlying mechanisms of a living being:

• Genetic mechanisms: the lowest in the hierarchy. The functioning of genes and their expression is essential, but they correspond to the basal substrate of any system.
• Mechanisms of cellular functioning: the next mechanism is that which concerns the cell, and thus the organs and tissues of the body.
• Nervous and endocrine mechanisms: these are the most advanced regulatory mechanisms in the evolutionary scale.

All living beings have genetic mechanisms, since by definition, a cell must have a genome to self-replicate on future occasions (even if it is only one chromosome, as in bacteria). On the other hand, every living thing must have at least one cellular regulation mechanism, since the basic unit of life is the cell, even if it makes up the whole organism (as is the case of bacteria and archaea).

As you can imagine, the pinnacle of physiological regulation mechanisms (glands and neurons, which are part of the endocrine and nervous systems, respectively) is restricted to the most evolutionarily complex animals, such as vertebrates, such as vertebrates.as we vertebrates are, although other living beings also have their own nervous and endocrine scales.

At this point, it should be noted that regulatory circuits can have two feedback systems: positive and negative. We explain briefly what they consist of in the following lines.

Negative feedback

In this case the regulation mechanism seeks to keep a parameter X under control in a very specific spectrum, always close to the value X0which is the maximum optimum in a given environment. The values of parameter X are collected from the environment or internal environment through the information channels (such as thermoreceptors and other nerve groups) and the information is taken to the center of the mechanism, which will generate responses based on the environment in the best possible way.

Positive feedback

In this case, things change. The aim of the positive feedback regulation mechanisms is to to reach the maximum point of effectiveness of the parameter X, deviated from the value X0, once certain conditions have been reached..

Although we are dealing with rather complex concepts, the difference between negative and positive feedback is very easy to understand: in the first case, the system responds to a direction opposite to the signal, i.e. it tends to "stabilize" the output of the system so that it remains under constant conditions. On the other hand, in positive feedback, the effects or outputs of a system cause cumulative effects on the input. In the latter case, it is a system that, by definition, has an unstable equilibrium point.

Examples of regulatory mechanisms.

We have moved between rather ethereal concepts, so it will come in handy to exemplify a bit what a regulatory mechanism is from a physiological point of view. Let's say, for example, that we want to understand how sweating occurs in humans. Let's get down to it.

First of all, it should be noted that sweating is a regulatory mechanism modulated by the sympathetic nervous system, which is responsible for many involuntary functions in the human being. Our hypothalamus contains neurons in the anterior and preoptic area specialized in registering changes in internal temperature and in the activity of the cerebral cortex. Therefore, when the information that there is an excess of heat (internal or external) arrives, the hypothalamus sends the signal through cholinergic fibers to the eccrine glands distributed throughout the skin to excrete sweat.

The sweat exits to the environment through the pores that communicate the eccrine glands with the skin. Since fluids need heat to evaporate (after all, heat is energy), they "catch" this excess temperature from the body surface, which causes our overall system to cool down. Evaporation of sweat dissipates 27% of body heat, so it is not surprising that this mechanism is triggered by any physical and/or environmental variation..

In this case, we are theoretically dealing with a negative feedback regulation mechanism. The interest of the organism is to maintain body temperature (parameter X) in a suitable range as close as possible to the ideal, which is between 36 and 37 degrees. In this system, the functional complex responds inversely to the external stimulus.

If we get philosophical, we can also conceive of natural selection itself or genetic drift as regulatory mechanisms from an evolutionary point of view. from an evolutionary point of view. Natural selection exerts pressures on the open system that is a population, selecting the most beneficial genes in the long term and discarding the less adaptive ones.

For example, an animal of a bird species that is born (by a de novo mutation) with a larger beak than the rest, could have a greater facility to hunt insects among the bark of trees. As this living being has an advantage over the rest, it will be able to feed more, will grow more and, therefore, will be stronger when competing with the rest of the males to reproduce. If the "big beak" trait is heritable, it is to be expected that the offspring of such an animal will be more viable than the rest.

Thus, over the generations, the "big beak" trait would increase in the population, as those with it would simply live longer and have more opportunities to reproduce. Natural selection acts as a clear mechanism of evolutionary regulation in this case, as the proportion of genes in a population varies according to the impositions of the environment.

Summary

As you may have noticed, regulatory mechanisms in the world of biology go far beyond thermoregulation or energy consumption. From the expression of genes to the evolution of species, everything can be summarized in a positive or negative feedback that seeks to reach a maximum point of effectiveness at one point or another.at one point or another. In the end, the goal is to reach the maximum internal balance in every possible way, always taking into account environmental impositions.

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