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Homeostasis is the process of physiological stability of a living organism

Image: John Jackson in Unsplash

The word homeostasis is derived from the Greek radicals homeo (the same) and stasis (to stay) and was coined by the American physician and physiologist Walter Cannon. The term is used to indicate the property of an organism to remain in balance, regardless of changes that take place in the external environment.

Homeostasis is ensured by a set of processes that prevent variations in an organism's physiology. If the conditions of the external environment are constantly changing, the homeostatic mechanisms are what guarantee that the effects of these changes on the organisms are minimal.

homeostatic mechanisms

The mechanisms that control body temperature, pH, volume of body fluids, blood pressure, heart rate and concentration of elements in the blood are the main tools used to maintain physiological balance. In general, these mechanisms work through a feedback negative.

O feedback Negative or negative feedback is one of the most important mechanisms for the maintenance of homeostasis. This mechanism guarantees an opposite change in relation to the initial change, that is, it acts to reduce a given stimulus, ensuring the proper balance for the body. The regulation of the amount of glucose in the blood is an example of feedback negative.

When we eat, the blood glucose level increases, stimulating the production of insulin. This hormone ensures that cells absorb glucose and store its excess in the form of glycogen, lowering blood sugar levels. When a reduction in glucose levels takes place, insulin stops being released. On the other hand, when sugar levels are below normal, glucagon is secreted. This hormone, unlike insulin, releases glucose that is stored in the form of glycogen, increasing levels of the substance in the blood. As glucose levels rise, glucagon secretion is stopped.

homeostasis division

Homeostasis can be divided into three subareas: ecological homeostasis, biological homeostasis and human homeostasis.

ecological homeostasis

Ecological homeostasis refers to balance at the planetary level. According to the Gaia hypothesis, elaborated by scientist James Lovelock, planet Earth is an immense living organism, capable of obtaining energy for its functioning, regulating its climate and temperature, eliminating its debris and fighting its own diseases, that is, as well as other living beings, the planet is an organism capable of self-regulation.

This hypothesis also suggests that living beings are capable of modifying the environment in which they live, making it more suitable for their survival. Thus, Earth would be a planet whose life would control the maintenance of life itself through feedback mechanisms and various interactions. From this point of view, the entire planet maintains homeostasis.

The concentration of carbon dioxide (CO2) in the atmosphere is an example. Without the presence of photosynthetic organisms, the levels of carbon dioxide in the atmosphere would be extremely high, obscuring the existence of oxygen and nitrogen gases. With the appearance of beings that carry out photosynthesis, the concentration of carbon dioxide substantially decreased, increasing the levels of oxygen and nitrogen gases, which allowed adequate conditions for the appearance and survival of other organisms.

biological homeostasis

Biological homeostasis corresponds to the maintenance of the internal environment within tolerable limits. The internal environment of a living organism basically consists of its bodily fluids, which include blood plasma, lymph, and other inter and intracellular fluids. Maintaining stable conditions in these fluids is essential for living things. If they are inconsistent, they can be harmful to the genetic material.

Faced with a certain variation of the external environment, an organism can be a regulator or a conformist. Regulatory bodies are those that expend energy to maintain their internal environment with the same characteristics. Conformist organisms, in turn, prefer not to expend energy to control their internal environment. Endothermic animals, for example, are able to maintain their body temperature constant through internal mechanisms. Ectothermic animals, on the other hand, need external heat sources to raise and maintain their body temperature constant. Therefore, mammals can spend long periods without being exposed to the sun, while reptiles and amphibians need the heat of the environment to keep warm.

human homeostasis

Human homeostasis is guaranteed by certain physiological processes, which occur in organisms in a coordinated manner. The mechanisms that control body temperature, pH, volume of body fluids, blood pressure, heart rate and concentration of elements in the blood are the main tools used in physiological control, as mentioned above. If these factors are out of balance, they can affect the occurrence of chemical reactions essential for the maintenance of the body.

Thermal regulation is an example of a physiological mechanism the body uses to keep its temperature constant. When we practice physical activity, our body temperature tends to rise. However, this change is captured by the nervous system, which triggers the release of sweat, responsible for cooling our body as it evaporates.

Conclusion

Keeping the internal environment in balance is essential for the proper functioning of the systems that make up the body of any living being. Enzymes, for example, are substances that act as biological catalysts, accelerating the speed of various reactions. To perform their function, they need a suitable environment, with temperature and pH within a normal range. Therefore, a balanced body is a healthy body.