A simple homeostasis definition: homeostasis is the process by which a living thing keeps its internal conditions, such as temperature, water and blood sugar, stable and within a safe range, even when the world around it changes. When you sweat on a hot day or shiver on a cold one, homeostasis is at work.
The word comes from biology, but people also use it more loosely for any system that keeps itself in balance, from a pond ecosystem to a company. Here you will find how it works in the body, everyday examples, a step-by-step feedback loop and how to use the word in a sentence.
Entry at a glance
Meaning
Keeping internal conditions steady in a changing environmentPart of speech
Noun (plural: homeostases, rare)Pronunciation
hoh-mee-oh-STAY-sisWord forms
homeostatic (adjective), homeostatically (adverb)Origin
Greek homoios (similar) + stasis (standing still); coined in the 1920s by an American physiologistOpposite idea
imbalance, disruption, instabilityRegister
Scientific; common in school biology and medicine
Define homeostasis in plain words
Think of homeostasis as a set of automatic adjustments. Your body has target ranges for many things, and it constantly checks and corrects itself to stay inside them. You do not have to think about it; it happens in the background all day and night.
The idea is a steady state, not a frozen one. Values move up and down a little all the time, but the body pulls them back toward normal. That is why the definition of homeostasis talks about keeping conditions relatively constant.
How the homeostasis definition works: the feedback loop
Most homeostasis works through negative feedback, where a change triggers a response that reverses that change. It has three main parts:
- Sensor (receptor): detects a change, such as a rise in body temperature.
- Control centre: compares the reading with the target and decides what to do. For temperature this is a part of the brain called the hypothalamus.
- Effector: carries out the fix, such as sweat glands releasing sweat or muscles starting to shiver.
Positive feedback, which pushes a change further, is less common and usually short-lived, for example during blood clotting or childbirth.
Everyday examples of homeostasis
| Condition | How the body adjusts |
|---|---|
| Body temperature | Sweating and widening skin blood vessels to cool; shivering and narrowing them to warm |
| Blood sugar | The pancreas releases insulin to lower it after meals and glucagon to raise it when it falls |
| Water balance | Kidneys make more or less urine; thirst tells you to drink |
| Blood pH | Breathing rate and kidneys keep blood slightly alkaline |
| Oxygen and carbon dioxide | Breathing speeds up during exercise to bring in oxygen and remove carbon dioxide |
Plants and single cells do it too. A cell controls what passes through its membrane, partly through processes like osmosis.
Homeostasis in sentences
- Our biology teacher used a room thermostat to explain homeostasis.
- Diabetes affects the body's ability to keep blood sugar in homeostasis.
- Shivering is one of the body's homeostatic responses to cold.
- Fever is a deliberate shift in the body's temperature set point, not a simple failure of homeostasis.
- Some managers talk about a team's "homeostasis", meaning its habit of drifting back to old routines.
Where the word comes from
Homeostasis was coined in the 1920s by an American physiologist studying how the body regulates itself. He built it from two Greek parts: homoios, meaning similar or alike, and stasis, meaning standing or a stable state. So the word means something like "staying similar". He chose "similar" rather than "same" on purpose, because the body keeps values close to a target, not perfectly fixed.
The underlying idea is older. In the 1800s, physiologists in France had already written about the body's stable "internal environment" as the condition for a free and independent life.
Using the word outside biology
In ecology, homeostasis describes how a natural system, such as a forest or lake, tends to recover balance after a disturbance; see ecosystem. In psychology and self-help writing, it can mean the pull toward familiar habits. Economists and engineers sometimes borrow it for systems with built-in correction.
These uses are metaphors. In school or a science exam, stick to the biological sense. Related ideas include entropy, the tendency of systems toward disorder, which living things must use energy to resist. Find more terms like this in science and ideas.
Frequently asked questions
What is homeostasis in simple words?
The homeostasis meaning for beginners: your body keeping things inside it stable, like temperature and blood sugar, while conditions outside change. It works automatically, like a thermostat for the body.
What is an example of homeostasis?
Sweating to cool down when you are hot is a classic example. Others include shivering in the cold and the release of insulin after a meal to bring blood sugar down.
What part of the body controls homeostasis?
Many organs take part, but the brain's hypothalamus is a key control centre, especially for temperature, thirst and hunger. The kidneys, pancreas, liver, lungs and skin also play major roles.
How do you pronounce homeostasis?
hoh-mee-oh-STAY-sis, with the stress on STAY. Some speakers say hom-ee-oh-STAY-sis with a short first vowel.
What happens if homeostasis fails?
Conditions drift out of the safe range, which can cause illness. Heatstroke, dehydration and uncontrolled blood sugar are examples of what can happen when the body cannot correct itself.
Is homeostasis negative or positive feedback?
Mostly negative feedback, which reverses a change and returns the body to normal. Positive feedback, which amplifies a change, is used only in a few special processes.