What is homeostasis

Homeostasis is the tendency not to stray from the range of favorable or ideal internal conditions. Such conditions must be kept the same constantly. Maintaining a stable internal condition is crucial to any form of living thing. In fact, this capability is one of the hallmarks of being alive. Instead of doing nothing, it acts upon and resists the effect of external factors so as not to deviate from the state of equilibrium, stability, or balance that it favors.

In humans, homeostasis is maintained through regulatory mechanisms, each comprised of three general components: a receptor , a control center , and an effector. The homeostatic mechanism may be in the form of a loop, which can either be positive or negative. Positive feedback leads to more stimulation or acceleration of the process whereas negative feedback leads to the inhibition of the source of stimulus or to the deceleration of the process. Examples of positive feedback are labor contractions at childbirth, blood clotting, and action potential generation.

Examples of negative feedback are thermoregulation, blood glucose regulation, baroreflex in blood pressure, calcium homeostasis, potassium homeostasis, and osmoregulation.

Homeostasis definition in biology is the ability or tendency of the body or a cell to seek and maintain a condition of equilibrium — a stable internal environment — as it deals with external changes. It makes use of feedback controls and other regulatory mechanisms in order to maintain a constant internal environment.

It can be construed as a skill of a living organism in its effort to stay within the optimal range despite the fluctuating environmental conditions. Thus, in the biological context, the word homeostasis entails multifarious physiological mechanisms in order to sustain and stabilize the functional, normal status of an organism. The concept of homeostasis was first described in by Claude Bernard, a French physiologist.

However, the term was coined later in by the American physiologist Walter Bradford Cannon. Variant: homoeostasis. An organism needs a system that effectively interconnects various biological processes and functions. The human body, for instance, has bodily organs made up of cells functioning in unison. These organs, although distinct from one another, have to work alongside each other in order to sustain a set of internal conditions within the ideal range.

There are various homeostatic processes and each of them works by regulating certain variables of the internal environment. The human body would not be able to function efficiently if there is a prolonged imbalance in the internal physical conditions and chemical composition. Just like any other living thing, the human body employs various homeostatic mechanisms to sustain its optimal functioning.

Variables such as body temperature, pH, sodium level, potassium level, calcium level, and blood sugar level have to be kept within the homeostatic range. The homeostatic range is defined as the allowable upper and lower limits for a particular variable. If beyond this range, the body would soon fail to carry out its tasks and become dysfunctional.

In order for the body to keep these variables within efficacious limits, various regulatory mechanisms are employed and each of them is comprised of three general components.

The components of homeostasis are: 1 a receptor, 2 a control center, and 3 an effector. The receptor , as the name implies, is the part of a homeostatic system that receives information regarding the status of the body. It monitors and perceives the changes in its environment, both the internal and the external. It is in the form of a sensory nerve terminal that receives the information i.

Examples of receptors in the human body are as follows:. The control centers pertain to the homeostatic component that processes impulses relayed by the receptors. Examples are the respiratory center and the renin-angiotensin system. The effectors are the target of the homeostatic response that would bring about the reversion of conditions to the optimal or normal range.

At the tissue or organ level, they are exemplified by the muscle or the gland. At the cellular level, they are the receptors of a nerve, including the nuclear receptors.

These three components work by first detecting and then responding to the information i. They respond to the detected change in the environment by relaying the information to the control center for processing , or directly to a particular target effector.

Processing in the control center entails deliberation and determination of the appropriate response to the relayed stimuli. Then, it sends this message to the effectors. The effectors upon receiving the message would bring about the supposed response that would revert to the normal homeostatic range. At the cellular level, the activated nuclear receptors will act upon by upregulating or by downregulating the expression of certain gene s. The protein produced from the gene expression would then exert its effect on the target organ.

Homeostatic mechanisms that respond to a perturbation may be in the form of a looping mechanism called feedback mechanism that may be positive or negative. Positive feedback maintains the direction of the stimulus. It tends to accelerate or promote the effect of the stimulus.

Examples are labor contractions, blood clotting, and action potential generation. Negative feedback is a self-regulatory system and is employed in various biological systems. It reverses the direction of the stimulus and tends to inhibit the source of stimulus or slow down the metabolic process. Examples include thermoregulation, blood glucose regulation, baroreflex in blood pressure, calcium homeostasis, potassium homeostasis, and osmoregulation.

Labor contraction during childbirth is positive feedback since the initial contraction of the uterine muscle leads to further contractions. It refers to how a person under conflicting stresses and motivations can maintain a stable psychological condition. A society homeostatically maintains its stability despite competing political, economic and cultural factors.

A good example is the law of supply and demand, whereby the interaction of supply and demand keeps market prices reasonably stable. Homeostatic ideas are shared by the science of cybernetics from the Greek for "steersman" , defined in by the mathematician Norbert Wiener as "the entire field of control and communication theory, whether in the machine or in the animal. Negative feedback is a central homeostatic and cybernetic concept, referring to how an organism or system automatically opposes any change imposed upon it.

For example, the human body uses a number of processes to control its temperature, keeping it close to an average value or norm of One of the most obvious physical responses to overheating is sweating, which cools the body by making more moisture on the skin available for evaporation. On the other hand, the body reduces heat-loss in cold surroundings by sweating less and reducing blood circulation to the skin.

Thus, any change that either raises or lowers the normal temperature automatically triggers a counteracting, opposite or negative feedback. Here, negative merely means opposite, not bad; in fact, it operates for our well being in this example. Positive feedback is a response to change from the normal condition that increases the departure even more.

For example, if a person's temperature is raised to about degrees Fahrenheit, the negative feedback systems stop operating. BCcampus; Your Privacy Rights. To change or withdraw your consent choices for VerywellMind. At any time, you can update your settings through the "EU Privacy" link at the bottom of any page.

These choices will be signaled globally to our partners and will not affect browsing data. We and our partners process data to: Actively scan device characteristics for identification. I Accept Show Purposes. Table of Contents View All.

Table of Contents. Maintaining Homeostasis. What Is Homeostasis? How Addiction Affects Homeostasis. Was this page helpful? Thanks for your feedback! Sign Up. What are your concerns? Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

Related Articles. What to Know About Deep Sleep. The 10 Best Sleep Gadgets of All About Catecholamines in the Stress Response. The 11 Best Pajamas of The 9 Best Pillows of The nervous system detects these deviations and reports back to a control center, often based in the brain. The control center then directs muscles, organs and glands to correct for the disturbance. The continual loop of disturbance and adjustment is known as "negative feedback," according to the online textbook Anatomy and Physiology.

For example, the human body maintains a core temperature of about When overheated, thermosensors in the skin and brain sound an alarm, initiating a chain reaction that directs the body to sweat and flush. When chilled, the body responds by shivering, and reducing blood circulation to the skin. Similarly, when sodium levels spike, the body signals the kidneys to conserve water and expel excess salt in concentrated urine, according to two NIH-funded studies.

Animals will also adjust their behavior in response to negative feedback. For example, when overheated , we may shed a layer of clothing, move into the shade, or drink a cold glass of water. The concept of negative feedback dates back to Cannon's description of homeostasis in the s, and was the first explanation of how homeostasis works.