We are hungry and we eat, because our body warns us that we lack nutrients. We are thirsty and drink, because we are in the process of dehydration and our body needs water to function well. Our pulse and breathing quicken in the face of an extremely activating situation and then we calm down, because we are no longer exposed to the situation that requires the use of energy.

If we observe all these relationships, we can realize that in all of them we are before a process that seeks to maintain a balance in our organism .

This balance is necessary for the correct functioning of our organism, so we carry out different processes to achieve it. We are talking about body homeostasis , which we will talk about throughout this article.

What is body homeostasis?

By body homeostasis we mean the tendency in the body to actively and constantly seek a state of balance, so that the cells of our body can survive by maintaining a stable internal composition.

The maintenance of this balance is fundamental, given that the activation or maintenance of different body processes requires energy, which in turn requires elements to be used as fuel. If these elements are not available, a series of damages to the tissues will be produced that can lead to death . The same thing happens if we are not able to activate or stop some of the aforementioned body processes, which are necessary for our survival.

It is important to bear in mind that homeostasis acts on the basis of the existence of changes that can occur both inside the body and from outside, also using mechanisms of action that link both environments (for example, hunger makes us eat).

The concept of body homeostasis, developed by Bernard but baptized by Cannon , does not speak of a situation in which the body remains unaltered in a position where there are always the same parameters, but rather of a dynamic balance between states that allows the values of the different components of our body to remain relatively stable, thanks to various biological mechanisms prepared for this purpose.

In this sense, it should be taken into account that living beings can withstand certain levels of variation and imbalance and that the mechanisms that allow homeostasis can be damaged or altered throughout the life cycle , which is important to take into account when introducing external factors that correct possible deficits.

Its components

For homeostasis to exist, three fundamental elements are necessary.

Firstly, it is necessary to have some kind of elements that act as a sensor, a receptor that allows the organism to capture the existing levels in the parameter or element that must remain in balance.

Secondly there must be some kind of control , a trigger that makes it necessary to act when certain levels are reached.

Thirdly and finally, it is essential that there is some kind of mechanism that allows a response or action to be taken once the control mechanism warns that the value of the variable or factor in question reaches the level of imbalance.

Processes for balancing the body

The homeostatic regulation process is complex and there are several mechanisms involved. Three of them can be highlighted: two of them are purely biological, while the third is more related to neuronal activity and behaviour.

Negative feedback

Negative feedback is probably the most logical and easily observed and understood mechanism of action of homeostasis.

This mechanism is based on the fact that, given the detection of a certain level of a specific parameter that is far from the normal values, a response is carried out that seeks to return this parameter to the previous stability .

Examples of this are set out in the introduction to this article. It should also be borne in mind that we are not talking about a search for balance that only occurs in situations where there is a lack, but also when there is an excess of something.

For example, in the case of variations in body water levels , thirst may arise if the body detects a lack of water or the need to urinate if there is an excess.

Positive feedback

Another process needed to maintain body homeostasis may, in fact, seem counter-intuitive. It is the positive feedback, which is characterized by an increase to amplification of the unbalancing stimuli, accelerating the changes.

This process can be risky and even dangerous for survival, but although it makes the organism move further away from the balanced baseline than it would initially, it has its uses: it may be necessary to perform this feedback or to move the baseline to a more optimal situation for survival or to achieve a return to initial situations in the long term.

Examples of this are the clotting of blood in the face of an injury, which becomes faster and faster and makes it easier to stop a bleeding.

Anteroalimentation

Feedback means that when a specific signal arrives, the organism generates some type of action that allows it to react to the existence of variations.

But is not the only way to maintain homeostasis : it is also possible to anticipate the arrival of changes and prevent them from occurring. This is the system that would be known as anteroalimentation, and at a biological level we would find it more linked to behaviour and the capacity of association, as well as to instinctive acts.

5 homeostatic processes that occur in our body

We have talked about body homeostasis as something general that may sound somewhat abstract to most readers (although several examples have been given).

But there are multiple aspects and functions of our organism that must be regulated to allow our survival. In order to make homeostasis much more visual, let’s look at five more examples (in addition to those already seen hunger, thirst, pulse and cardiorespiratory rhythm or blood coagulation) of elements that are regulated and that allow the correct functioning of our system.

1. Cellular metabolism

The cellular metabolism is without a doubt the process that needs more regulation in order to keep us alive. Our cells are very delicate and need to be in a very specific environment.

It is necessary that the levels of different elements and ions of elements such as sodium , potassium or calcium, as well as the levels of intracellular fluid and extracellular fluid, are properly regulated in order for the cells to perform their functions and remain alive.

2. Body temperature

Another body mechanism that is continuously regulated is the internal body temperature. The correct functioning of our tissues and organs can be affected by excessive heat or cold , to the point of leading to death from hypothermia or hyperthermia.

Fortunately our body is able to maintain temperature through a homeostatic process in which if there is an excess of internal temperature the body reacts with a decrease in physical activity, discomfort and sweating (whose aim is to reduce the temperature) or with an increase in activity, generating tremors, consumption of calories , removing the blood from secondary areas to direct it to vital areas and seeking heat in the case of lack of sufficient temperature.

3. Autonomic nervous system

The functioning of the autonomic nervous system is another clear example of homeostasis.

The sympathetic system allows the organism to prepare itself for action and the fight or flight reactions in order to survive, generating a much higher energy consumption to be able to carry out the necessary actions, while the parasympathetic system allows us to reduce activity and activation in order to replenish energies or prevent energy waste.

An example of dysregulation would be in chronic stress problems , in which the sympathetic system would be excessively activated on a continuous basis.

4. Regulation of glucose

In this case, our body acts in such a way that it allows sugar to be transformed into fat and stored thanks to insulin, while when it becomes necessary for the body to use glucose, we secrete glucagon in order to transform fat into sugar. The clearest example of dysregulation is in diabetes .

5. Hormone regulation

Also the endocrine function has to be regulated. In fact, many of the behaviours that lead to externally generated homeostasis, such as feelings of hunger or thirst, sexual desire or stress, depend to varying degrees on this system.

A natural and non-pathological example can be found in the female menstrual cycle , as well as in the dysregulation that menopause would initially entail.

Bibliographic references:

  • Hardy, R.M. (1979). Homeostasis. Biology notebooks. Omega: Barcelona.
  • Guyton, A.C. & Hall, J.E. (2016). Treatise on Medical Physiology. 13th ed. Elsevier.
  • García, A. (2016). Homeostasis: regulation and control. Universidad Autónoma del Estado de México. Faculty of Medicine.