The term homeostasis originates from two Greek words – homeo, which means “similar” or “identical” and stasis, which means “standing” or “stable”. The closest translation of the term is “staying the same”. Homeostasis identifies a state when a living system reaches internal equilibrium. All systems aim to reach a balanced state, but the term “homeostasis” is used only to explain how biological systems alter their internal processes in respond to changes in the environment and to ensure the proper functions of the system components. Homeostasis is not a static state, but a dynamic one – ever-changing state. It is important to state that it differs from other similar phenomena (like dynamic equilibrium) because it is a regulated process.

What Is Homeostasis On Biological Level – Living organisms

Based on the selected approach for maintaining homeostasis, the organisms could be classified into conformers and regulators. The first group accepts the environment to define their system parameters, while the second group tries to maintain their system parameters to a certain range. One of the classical examples of homeostasis conformer’s approach is the ectothermic animals, whose body temperature is dependent on the environmental temperature. The endothermic animals could be used as an example of homeostasis regulators, because they are able to maintain their body temperature in a certain range.

Homeostasis Control Mechanisms

The whole body balance is maintained by the interactions between components of multiple systems and primarily by the nervous and endocrine systems taking. One of the common examples of human homeostasis is the regulation of the body temperature – when the temperature is high, a center within the brain recognize this change and induce the excretion of the sweat glands to decrease the temperature; when the temperature is low, then the muscles shiver to generate heat.

From the example above, it could be inferred that the homeostatic regulation of body condition variables requires three mandatory components:

Receptor brings the external signals to the system that responds to external changes. If the receptor captures a signal above a defined threshold, it “transmits” the information to a control center.

brings the external signals to the system that responds to external changes. If the receptor captures a signal above a defined threshold, it “transmits” the information to a control center. The control center determines an appropriate corrective response to the external stimulus. For vertebrate animals, in most homeostatic mechanisms, the control center is the brain.

determines an appropriate corrective response to the external stimulus. For vertebrate animals, in most homeostatic mechanisms, the control center is the brain. Effectors receive the “instructions” from the control center. The effectors involved in homeostasis are usually muscles, organs, glands or other formations with specific functions.

Based on the specific process and the received signal, the biological system (in this case, the organism as a whole) makes appropriate changes to correct the deviation by either amplifying it (positive feedback) or suppressing it (negative feedback).

Positive Feedback of Homeostasis

Positive feedback mechanisms aim to increase or speed up the system respond created by an external stimulus. The result of a positive feedback mechanism is to push the body parameter levels out of normal ranges. This can be achieved by initiation of a cascading process that leads to increase the effect of the stimulus. This cascading amplification not used frequently by the body because does not allow fine tuned control mechanism. An example of homeostasis positive feedback mechanism is the release of hormone oxytocin during childbirth, which intensifies the muscle contractions and facilitates the birth of the baby.

Negative Feedback of Homeostasis

Negative feedback homeostasis mechanisms aim to put the functioning of any organ or system back to its normal range. A classical example of negative feedback of homeostasis is blood pressure regulation. Blood vessels a rigid and can register the increased pressure of blood flow towards the walls. So, they acts as receptors and transfer this signal to the control center – the brain. Then the control center sends a message to effectors – the heart and blood vessels. The blood vessels increase their diameter (known as vasodilation) and as a result the heart rate slows down. The overall effect is that the blood pressure will go back to its normal range. In case of low blood pressure, happens just the opposite – when blood pressure decreases this would cause decreasing the blood vessel diameter (known as vasoconstriction).

Homeostatic Imbalance and Disease Conditions

A deviation observed for any of the body’s homeostatic processes (body temperature, blood pressure, levels of blood sugar), can be used as a sign of a potential medical condition and is usually used for the diagnosis in the medical practice. Heat shocks, dehydration, bacterial and viral infections, dehydration, and hormonal diseases are common examples cases when the body alone cannot fix a specific imbalance. Imbalance could be also caused by introducing external agents into the organism, although intending a medical benefit – for example, antibiotics treatment has toxic effect over the normal bacterial gut flora and could lead to digestive system disturbance and overall organism discomfort.

What Is Environmental Homeostasis Or Homeostasis In Ecosystems

Homeostatic mechanisms exist and in larger biological systems, like ecosystems. Homeostasis help achieve balance in ecosystems – a phenomenon known as environmental homeostasis. In grasslands ecosystems, the population of rodents remains fairly constant from year to year. The maintenance of the rodents population within a certain boundaries is a net effect of the environmental factors (like climate, other natural systems, food supplies, water, etc) but also results from the effect of the predators (canine, hawks, and other predators) over the studied population of rodents.

In such ecosystems, the maintenance of the equilibrium can be quite complex. Abundant rain may lead to increased amount of seeds, with which rodents feed. In turn, this will cause an increase in the rodent population. Finally the different populations of predators may also increase because of the increased food supply provided by the expanded rodent population.

However, the over-increased predator population or accidental drought in succeeding years, may lead to decrease of the rodent populations, which in turn will result to a decline in predator populations. Such environmental homeostasis maintain a balance between food in the ecosystem and different populations of species.