6. Homeostatic resilience

Summers are getting hotter and weather conditions are becoming more extreme. All living things try to cope with these strong fluctuations while keeping their own system constant. Our body is no exception: ideally, when temperatures rise, our own body temperature does not rise, but we sweat so that the excess heat leaves our organism. Cooling down through sweating, however, also means work for the body and therefore increased energy consumption. The heart rate increases and the energy needed for cooling down must be replenished quickly - but at the same time is also lacking in other areas. This is why we feel weak, get tired more quickly and are not able to exercise as vigorously.

There are some physiological functions that are always kept in balance so that our body functions. This balance is called homeostasisThe body’s ability to maintain this balance even under extreme conditions – such as heat in this example – is then called homeostatic resilience.

The term resilience is more commonly known from psychology and describes the resistance to stress or the ability to deal with difficult situations. Physiological parameters that are kept in balance include blood pressure, arterial oxygen capacity, heart rate, body temperature, hormone levels, pH value or body temperature. These values ​​cannot be kept completely static, but fluctuate "homeodynamically" within a buffer capacity. The larger the buffer capacity, the higher the resilience of the system.

Neural mechanisms – homeostatic resilience in the brain

As the central control system of the body, the brain with its neuronal circuits is also the first port of call for homeostatic regulation. In order to react to external influences and to adjust and balance the internal equilibrium, our body works a lot with hormones. The release of hormones is mostly controlled by commands from the brain. The main control over this lies in the hypothalamus and the spinal cord. This is where two central axes of the nervous system begin that regulate the production and release of hormones.

The faster axis activates the release of hormones in the adrenal medulla, starting from the spinal cord. It is part of the sympathetic nervous system and is known as Sympathetic-adrenal medulla axis (HNA). In the adrenal medulla Adrenalin and Norepinephrine produced. The second axis (HPA) activates the release of glucocorticoids in the adrenal cortex. The control for this is located in the hypothalamus, which causes the pituitary gland to release the adrenocorticotropic hormone (ACTH). This hormone then activates the release of glucocorticoids in the adrenal medulla. These intermediate steps make the system significantly slower.

The release of stress hormones serves as a protective mechanism for the body. However, a stress reaction that lasts too long and/or is too intense can have a harmful effect on the body. From a medical point of view, “peeing your pants out of fear” is therefore not sensible

Metabolism – anabolism and catabolism

In addition to neuronal mechanisms, metabolic cycles are also involved in the balance, which is controlled by hormones. As you may know, metabolism refers to the metabolism and can be divided into anabolism and catabolism. You are most likely familiar with anabolism from the term anabolic steroids. These promote muscle building and are often used, but forbidden, in bodybuilding. Anabolic processes build up the body's own substances and usually use energy in the process. The counterpart to this is catabolic metabolism. Here, the body's own substances are broken down and energy is released. A very simple example of these two opposing metabolisms is the storage of body fat (anabolic) and the breakdown of body fat (catabolic).

Fat as an underestimated good

Fat - whether as a food component or as extra fat on the body - is often viewed negatively in our society. Unjustly so. Fat can do a lot. Among other things, it can supply and store a lot of energy. One gram of fat can store and supply more than twice as much energy as the same amount of carbohydrates. It is the most efficient source of energy. That is why the body stores most of its excess energy in fat, so to speak, to create reserves for worse times and not to waste energy - this is anabolism.

However, as with everything, the dose makes the poison. Too much body fat and too much fatty food massively increase the risk of cardiovascular disease and other illnesses. However, it is important to know that a high body fat percentage does not automatically indicate a person's lifestyle. Some illnesses encourage the storage of fat and those affected suffer both the physical and psychological consequences due to stigma. The breakdown of body fat occurs when the body has no other energy sources available. The energy of the body fat is then used - this is called catabolism.

Back to homeostasis: A good balance between anabolism and catabolism and good resilience in the face of major fluctuations tends to indicate good health and therefore increased longevity. A constant and excessive change between building and breaking down processes would stress the body.

Immune system and homeostatic resilience

Repeated outbreaks of disease show us again and again: a good immune system is a pillar of our health. If an infection hits our body, the innate and acquired immune systems have a number of tools at hand to deal with it. It is neither good if the immune system overreacts to a harmless infection, causes high fever and inflammation, and thereby damages itself. Nor is it good if the immune system does not react at all and the infection can simply spread as a result.

As you already know in Hallmark of Health Articles about the Circuits As you have learned, almost all functions of the body are connected and dependent on each other in a certain way. For example, an increased level of cytokines (these are messenger substances of the immune system that activate inflammation and immune reactions) causes the activation of the HPA axis. As a reminder: Glucocorticoids such as cortisol are released via the HPA axis.

At the same time, however, they also affect the receptors on which glucocorticoids act. The receptors are then no longer able to transmit the effect of the glucocorticoids as well and the actual reaction occurs only to a reduced extent. A kind of glucocorticoid resistance occurs because they are released but no longer have any effectOne function of glucocorticoids is normally to downregulate cytokines and thus inhibit the immune system. However, when such a loop occurs, the cytokines can no longer be downregulated and a vicious circle begins - homeostatic resilience is reduced.

Microbiom

It is now widely recognized that the gut and the microbiome are important cornerstones of health. The intestinal barrier ultimately influences which of our food actually ends up in the bloodstream and thus becomes biologically active. The interaction is described in professional circles as the microbiome-gut-brain axis. If the flora in our gut becomes unbalanced, this has an impact on some other bodily functions, such as the immune system or the psyche.

Every person has an individual flora that can sometimes become unbalanced. The microbiome can be damaged to a greater or lesser extent, particularly by serious illnesses. A resilient microbiome means that even when there are fluctuations, the effects are not so great and the body has the ability to balance out these fluctuations well and thus contribute to an overall healthy body. The foundation for this is laid in childhood. Those who have built up a stable and well-functioning microbiome as children are usually better able to cope with later deviations.

Conclusion Homeostatic resilience 

In life, the entire body reacts to external and internal fluctuations with adjustments on various levels. You can imagine these cycles like a sailboat on the high seas. External circumstances such as high waves or strong winds can throw the boat out of balance and require a good team on the boat to restore balance by making appropriate adjustments to the sails and shifting weight. The boat can also be upset by crew members, incorrectly hoisted sails or material problems. In any case, readjustment is required on many levels.

The better and more calmly the boat itself sits in the water and the better the crew members know the sailing ship and work together, the more likely it is that a good balance can be restored from turbulence. Well-coordinated and resilient individual components make the entire system more secure against threats.