Homeostasis: What It Is and How It Works

Medically Reviewed by Poonam Sachdev on January 18, 2023
8 min read

homeostasis infographic

Homeostasis refers to any automatic process that a living thing uses to keep its body steady on the inside while continuing to adjust to conditions outside of the body, or in its environment. The body makes these changes in order to work the right way and survive. When it does this successfully, it will continue to live. When it is unsuccessful, it can cause imbalance, leading to disease or death.

In a state of homeostasis, body levels are constantly rising and falling in response to changes outside and inside the body. Some of the systems that self-regulate to stay at normal levels are:

  • Blood sugar
  • Blood pressure
  • Energy
  • Acid levels
  • Oxygen
  • Proteins
  • Temperature
  • Hormones
  • Electrolytes

Any bodily system in balance reaches a steady state that can withstand outside forces of change. When this system is disturbed, controlling devices built into your body react to create a new balance. 

One process is called feedback control. All processes that involve carrying out and controlling a function are examples of homeostasis. This occurs whether it's made possible by the nervous system, hormonal system, or electrical currents.

An easy example of regulation via homeostasis is a system that controls the temperature in the room -- a thermostat. The center of the thermostat is a metallic strip that can sense temperature changes and react by controlling an electric circuit.

When the room is cold, the furnace is triggered by the thermostat, causing the temperature to go up. When the preset level of the thermostat circuit is reached, the furnace stops, and the temperature will remain the same or go back down. This process is somewhat similar to certain processes within your body, such as:

Body energy. Think about how much food you need to go about your day. Typically, when we get hungry, we eat. But if we stop having as much food, we can still function just fine. That's because of homeostasis. With access to less food, our bodies react by setting a "new normal" that demands less energy and a slower metabolism rate for our bodies to work. Without homeostasis, our cells would quickly die when there aren't enough nutrients. Instead, we're able to live on less food as long as we can keep our energy levels the same.

Body temperature. Whenever you sweat while exercising, that's homeostasis at work too. An area of the brain called the hypothalamus can pick up on even the slightest change in body temperature and tell your body to adjust to stay in balance. When you're too hot, you sweat to lower your temperature. When you're too cold, you shiver to help bring it back up.

Blood pressure. When your blood pressure rises, your blood vessels can tell there's more resistance to blood flow. They tell the brain this is happening, and the brain communicates with the heart and blood vessels in response. This causes the heart rate to slow as the blood vessels open up more, allowing your blood pressure to return to normal. The opposite happens when you have low blood pressure.

While homeostasis describes how the body tends to create balance within itself in response to stress or changes it feels in real time, allostasis refers to our body's ability to foresee, adapt to, and deal with future events. More specifically, allostasis is preparing for needs and managing resources to meet those needs before they arise.

These two responses are also different in another way. Homeostasis manages the systems that are needed for life, while allostasis keeps these systems in balance.

One example of allostasis is a bird adapting to the seasonal demands it expects every year. In the spring, it will expect a lot of food so it has the energy to mate and raise its hatchlings. Allostasis is also what helps us lower the chances of uncertain outcomes by predicting our needs and planning to meet them ahead of time.

Homeostasis involves three mechanisms: the receptor, control center, and effector. These all work together to help keep your body in balance by noticing changes and then acting upon them to regulate your systems.

Receptors. Often cells, tissues, or organs, these elements track your environment and spot any changes. When they do, they notify a control center.

Control center. Also known as integration centers, these are often found in the brain and are responsible for defining what the "normal" balance is in the body and what to do to correct anything that strays from that normal state. The control center will then tell effectors to put that course of action into motion.

Effectors. These cells, tissues, and organs will cause your body to react to correct any kind of imbalance, restoring balance. For instance, sweating is the effector that lowers your body temperature when you get too hot.

An important part of homeostasis is that the living thing's internal environment is maintained through a self-regulating system that works within a narrow range of values. Both feedback and feedforward are ways that homeostasis is maintained. A feedback system is defined as a closed-loop structure that controls future actions by feeding the past changes in the internal environment into the system. The system then changes its behavior to adapt to external conditions.

There are two types of feedback systems. They are negative and positive. Negative feedback seeks a goal and responds to any failures to meet that goal. It keeps a steady range of values.

Positive feedback creates processes of growth, where actions take advantage of the results that in turn would build greater actions. An example of positive feedback would be blood clotting. When you get wounded and start bleeding, positive feedback quickens the clotting of your blood, which leads to stopping your blood loss. These systems of feedback are subject to levels of higher control and may be opposed by negative feedback.

The operation range involves variables that are controlled and can respond to stimuli from the environment. These complex interactions and the competing negative and positive feedback systems result in homeostasis, which is the foundation of physiological regulation or how our bodies are controlled.

Homeostasis is the central concept that brings together physiology and self-regulation to keep internal things stabile. Homeostasis is not constant. It's an active, changing process that changes internal conditions to encourage survival.

Control via homeostasis is not a single feedback cycle. It reflects the complex relationship of many feedback systems controlled by nerves and hormones. This feedback results in a precise level of control and flexibility that allows an organism to adjust to changes in environmental conditions.

The life and health of an organism are the results of being able to regulate via homeostasis. The interruption of homeostasis is what causes disease.

Proper treatment and therapy must be aimed at resetting conditions of homeostasis. Otherwise, it could lead to severe disease or death.

Body temperature control is a good overall example of how your body keeps balance. In humans, 98.6 F is the average body temperature. Various factors could affect this number, including:

All of these factors can lead to extremely low or high temperatures. Your body temperature is then controlled by the brain, though, in an area called the hypothalamus. Body temperature feedback is carried through the nervous system to your brain. This results in adjustments in your blood sugar levels, breathing rate, and metabolic rate in an attempt to return to homeostasis.

Heat loss in your body is affected by sweating, decreasing activity, and heat exchange functions that allow large blood amounts to flow at the skin's surface. Heat loss is reduced by decreased skin circulation, insulation, and outside adjustments. Examples include seeking shelter, clothing, and external sources of heat.

The difference between low and high body temperatures is a homeostatic plateau. This is the normal range that allows life to continue. As temperature levels approach either low or high, correction through negative feedback helps the system to return to a normal range.

Your body also keeps homeostasis through the circulatory system and baroreceptors. Baroreceptors are pressure-sensitive areas in the blood vessels that react to stretching. They send blood pressure information to your brain, which sends hormones made by the thyroid gland and the hypothalamus to control metabolism in your body.

Glucose homeostasis

Your pancreas is constantly working to keep your blood sugar levels in the right place through glucose homeostasis. When they're high, the pancreas releases insulin into your blood to soak up extra glucose from your blood and bring levels back to normal. This could happen after you eat a meal, for instance.

When your blood sugar gets low (for example, when you sleep, fast, or if you're in between meals), the pancreas releases the hormone glucagon into the bloodstream, which tells your body to break down stored carbs and sugars and release them into the blood until your blood sugar is back to normal.

Diabetes happens when this homeostasis doesn't work properly, so there's no automatic regulation. Instead, you need medicine and treatment to restore blood sugar balance.

Homeostasis has been used in ecology too. First introduced by ecologist Robert MacArthur, an understanding of homeostasis in ecosystems is created by combining a variety of living things in the environment and interactions between different species. It was believed that the concept could explain stability in the ecosystem. It has evolved over the years to include nonliving parts and is seen by some as controversial.

Homeostasis allows us to automatically adjust in order to adapt to sudden changes inside and outside the body. It's managed by a three-part mechanism. Receptors sense change and communicate to control centers in our bodies, which tell effectors to react to that change. All of this ensures our bodies work at the right level, allowing us to continue living despite the unexpected things we face daily, such as a lack of food or cold weather. When homeostasis doesn't work right, it could lead to disease or death.

How does water help maintain homeostasis?

Water helps control body temperature. It does this by absorbing heat, spreading it out among the liquid parts of the body, and getting rid of it through sweat. Water also plays a role in blood pressure management. For instance, if blood pressure is too low, the kidneys will retain water.

Which body systems help maintain homeostasis?

Homeostasis involves all organs of the body, with different systems acting together to keep it in balance. This includes:

  • Integumentary system
  • Nervous system
  • Musculoskeletal system
  • Cardiovascular system
  • Endocrine system

What improves homeostasis?

Many things can help support homeostasis across different systems. For instance, you can improve your immune system's homeostasis with plenty of sleep and nutritious food. Exercise can help improve blood sugar homeostasis. You can also improve homeostasis, particularly in your immune and nervous system, by avoiding ongoing stress, through things such as coping skills, support, and meditation.