Homeostasis: The balance the body needs


The environment we live in is constantly changing. Since the environment affects the body, there must be a mechanism that guarantees balance in and out of the body. This mechanism is called homeostasis. Whenever homeostasis is disrupted, the body falls in danger. Generally, living beings need nutrients, water, and oxygen to survive. Strangely, the body does not rely only on these to survive. Disruption of some other components may cause the body to break down. Do you want to know? Let’s find out.


The human body is constantly at work; when you are eating, sleeping, or talking. The human body will in its capacity ensure that your internal environment is always kept constant or unperturbed by your external environment. Regardless, it has a limit and when pushed beyond its limit, will bring down resulting in a disease or even death.

Aside from water, nutrients, and oxygen, the human body relies on a balance between temperature, salt concentration, pressure, pH, and others to function properly. For instance, an overheating in your mobile phone or computer will cause the machine to freeze or malfunction, similar instances happen in your system.

How homeostasis happen

Homeostasis, from the Greek words for "same" and "steady," refers to any process that living things use to actively maintain fairly stable conditions necessary for survival. The term was coined in 1930 by the physician Walter Cannon.  The body has an average number which is a physiological value and the point at which the normal range fluctuates is called the set point. The normal range is a range of numbers around the set point for which an individual may be considered stable and fit. For instance, in humans, the setpoint for body temperature is at 37degrees Celsius (37°C).  When there is a significant increase or decrease in the setpoint, the body engages in several activities to return it to normal. If these set of activities should fail, an individual will be in danger and risk getting several complications. To achieve this, the body uses a mechanism called the feedback loop to restore settings to normal. The feedback loop consists of 3 major components:

• A  sensor
• A control center
• An effector

1. The sensor

The sensor as its name suggests senses changes within the normal range. It is able to detect a significant deviation in the environment. This change or value is reported to the control center. The sensor is sometimes referred to as the receptor.  The sensor communicates with the control center via hormones or nerve cells.

2. The control center

The control center is the region that compares the value to the normal range. If there is a huge deviation from the set point, the control center will activate the effector. An example is the hypothalamus in the brain.

3. The effector

The effector is the component that acts on the state or deviated action and brings it back to normal. The effector generally effects a change. Effectors are usually made up of muscles and glands.
The feedback loop system can be either positive or negative.

Positive feedback mechanism

In positive feedback, the effector intensifies the stimulus rather than reversing it. However, a bigger change returns the system to normal.  Positive feedback is normal only when there is a definite endpoint.   Example are:

  1. Childbirth

During delivery, oxytocin is released. Instead of the hormone being returned to normal, the brain responds by producing more oxytocin. As more oxytocin is produced, it causes more contractions that cause the baby to be pushed from the uterus to the opening of the cervix and pulled out.
2. Injury
When a person gets injured or a cut, the injured blood vessel becomes open. Certain substances in the blood work to clot the blood. As more clotting substances are released, the faster the clotting occurs hence preventing major blood loss.

Negative feedback mechanism

In negative feedback, the effector goes to reduce the intensity of the stimulus or shuts it off completely. The negative feedback mechanism is the most common way the body uses to restore balance. Examples of negative feedback mechanisms are:

  1. Regulation of blood glucose level
    Blood contains oxygen as well as nutrients that are circulated around the body. An example of such a nutrient is glucose. However, glucose in the blood at any point must be around a set point. If the glucose level in the blood is too high, special endocrine cells in the pancreas detect these changes. These cells respond by secreting the hormone insulin into the bloodstream. The hormone works by signaling the skeletal muscles, liver cells, and fat cells to remove the excess glucose from the bloodstream. When the glucose level reaches the normal range, the cells detect it and the release of insulin is brought to a halt.  If the negative feedback system does not work, it may lead to diabetes which is harmful to the body.
  2. Temperature regulation (Thermoregulation)
    Temperature is an important factor when dealing with human cells. When the difference between the external and internal environment is huge, the body acts quickly to restore balance.
    In the presence of a warm environment, receptors in the skin detect changes and inform the hypothalamus (control center) in the brain quickly. The hypothalamus commands the blood vessels in the skin to dilate(expand) allowing more blood from the core of the body to the surface of the skin to radiate heat. The sweat glands become activated to release sweat. As sweat evapourates from the skin, it takes heat with it and cools the surface of the skin.

During vigorous exercises, the sweat glands open up. In addition, respiration increases, and the individual may breathe through an open mouth(panting) instead of the nasal passageway. This reduces the heat from the lungs.
In the presence of a cold environment, blood flow to the skin surface is reduced which traps heat inside the body. In severe cold conditions, the hypothalamus activates the skeletal muscles to contract which produces shivering. The contraction releases heat in the process.

There are some behavioral and physical activities that may be performed during homeostasis. For instance, in cold weather, an individual may drink hot drinks and wear thick clothes. In warm conditions, you will go for cold drinks and thin clothes.
The next time you engage in such an activity, remember, that it is your body’s mechanism to keep you stable and fit.


  1. Scientific American. What is homeostasis? Retrieved from https://www.scientificamerican.com/article/what-is-homeostasis/#:~:text=Homeostasis%2C from the Greek words,by the physician Walter Cannon.
  2. Lumen-Anatomy and Physiology. Homeostasis. Retrieved fromhttps://courses.lumenlearning.com/nemcc-ap/chapter/1558/


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