Body processes

Homeostasis – Function, Task & Diseases

Homeostasis

The term homeostasis comes from the Greek and means equality. It describes a process that serves to maintain an equilibrium within dynamic systems. In the human body, the internal milieu is maintained by homeostasis. Examples of homeostatic processes are thermoregulation or the regulation of blood sugar levels .

What is homeostasis?

All control processes in the body strive for balance. Equilibrium states are the basis for many organ functions and for the survivability of the entire organism. Homeostasis in the body is maintained by mechanisms such as control circuits or redundancies. These mechanisms give the body the ability to self-regulate.

The aim of homeostasis can be to maintain balance within a single cell , within cell groups, in an organ or in the entire organism. The preservation processes can relate to anatomical structures, chemical or physical processes or even to mathematical factors such as the number of cells in a specific structure

Function & task

In many cases, homeostasis is maintained by regulatory systems with negative feedback . A target value is first determined. This is the value that guarantees optimal conditions for safety, survival and well-being. A sensor, which can be the pituitary gland or the hypothalamus , for example , compares the current value with the target value. If a discrepancy between the target value and the actual value is detected, a regulating process starts. This typically only ends when the discrepancy between the two values ​​has disappeared.

An example of such a negative feedback system is thermoregulation. The target body temperature is usually between 36.5 and 37 °C. The current body temperature is registered by so-called thermoreceptors, which are located in the hypothalamus in the brain . In the event of deviations from the desired temperature, the hypothalamus can initiate measures that bring the temperature in the desired direction. It can cause sweating or tremors due to changes in the blood vessels . Also, the hypothalamus can prompt people to dress warmer or colder, or to move from the sun to the shade.

Similar homeostasis processes exist for numerous functions of the body. When the blood sugar drops, the feeling of hunger follows relatively quickly , and when the salt content of the blood is too high, people feel thirsty .

Sleep regulation is also based on a homeostatic process. Sleep duration and sleep intensity are regulated on the one hand by the circadian rhythm and on the other hand by the homeostatic sleep pressure. To a certain extent, the circadian rhythm reflects the internal clock. It ensures that we are tired at around the same time every day. The homeostatic sleep pressure, on the other hand, depends on previous wakefulness. The longer and more strenuous the waking phase, the higher the homeostatic sleep pressure.

One of the most important homeostasis of the human body is the homeostasis of the brain. To keep the environment in the brain in balance, there is a barrier between the bloodstream and the central nervous system . This is known as the blood-brain barrier . The blood-brain barrier protects the brain from pathogens, hormones or toxins. You cannot pass through this filter. Other substances such as nutrients can cross the blood-brain barrier. This maintains homeostasis in the brain.

Diseases & Ailments

Disturbances of the homeostasis lead to functional disturbances in individual organs or even in the entire organism. Many homeostasis disorders originate in the hypothalamus. If central impairments occur here, the body temperature can be permanently too low or too high. Fever phases often alternate with phases of hypothermia. For example, those affected freeze during the day and sweat so much at night that they have to change their bedclothes and bedclothes several times.

Obesity and eating disorders are also often based on a disturbed homeostasis. Researchers suspect that many diets have a negative impact on the regulatory system for satiety and hunger until normal regulation is no longer possible.

Disturbed sleep homeostasis causes insomnia and difficulty falling asleep. Alcohol in particular appears to play an important role in disorders of sleep homeostasis. Alcohol increases homeostatic sleep pressure, which means the need to sleep increases. As a result, the sleep period is shifted and sleep is not as solid as usual. Alcohol reduces the quality of sleep by disturbing the homeostatic pressure.

Blood sugar homeostasis is essential for survival. Hypoglycaemia leads to reduced brain performance, seizures , sweating and, in an emergency, to shock . Hyperglycemia , on the other hand, is manifested by severe thirst, deepened breathing and subsequent loss of consciousness .

A disturbance in the homeostasis of blood sugar can also lead to a regulatory disturbance in the pH value of the blood. The reference range of pH for humans is between 7.35 and 7.45. Outside of these values, homeostasis is disturbed. A lower pH value is referred to as acidosis (overacidification), and a higher pH value is referred to as alkalosis . pH homeostasis is maintained via the kidneys and lungs . If certain metabolites are increasingly produced or if the excretion capacity of the kidneys and lungs is restricted, acidification or increased pH values ​​can occur.

A homeostasis disorder is also suspected to be the cause of Parkinson’s disease. Disruption of ionized calcium homeostasis appears to have negative effects on dopamine production . In Parkinson’s disease, characteristic symptoms such as muscle rigidity, muscle tremors or postural instability occur due to a lack of dopamine.

When brain homeostasis cannot be maintained due to impairments in the blood-brain barrier, diseases such as meningitis (an inflammation of the meninges) or encephalitis (an inflammation of the brain) occur. Alcohol, nicotine and electromagnetic waves affect the blood-brain barrier and increase susceptibility to neurological diseases.

Lisa Newlon
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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.