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How does the body respond?

Explore homeostatic control systems; how does the body respond to stimuli? What are receptors and effectors? Find out in this article.
person holding hot drink with steam coming off

So how does our body respond in a homeostatic way to external or internal influences?

Every day, the right responses to stimuli must be made and coordinated. The body must carry out tasks from regulating respiratory gases to maintaining constant body temperature. This is what maintaining homeostasis is. It is maintained through a combination of hormonal and nervous mechanisms.

There are three key components of a homeostatic control system. These are the:

  • receptor
  • control centre
  • effector.

The receptor is something that picks up or detects a change and then sends the message to the control centre which is usually the brain. Once the brain has processed the information it will then send out a response message to an effector which makes change happen.

In the illustrated example below, heat receptors (receptors) in the skin detect heat when the person touches fire. It sends a message to the brain (control centre) which then sends a message to the muscles in the hand (effectors) to move the hand away from the heat!

sequence of three things 1-hand touching fire, 2-brain, 3-hand is removed Click to enlarge the image.

Another example of this process is when carbon dioxide (CO2) is detected by chemical receptors (receptors) in the body, which send a message to the brain (control centre). It then sends a message to the respiratory system (effectors) to breathe faster and deeper to remove the CO2 and increase the level of oxygen in the blood.

Examples of homeostatic control systems

There are some examples of homeostatic control systems below. Each system requires co-ordinated efforts from multiple organ systems like the cardiovascular or digestive systems.

The first table names some systems that control the body’s internal temperature, despite what the external temperature is. It can use multiple organ systems to help maintain homeostasis. For example:

System Function
Integumentary system (skin) Can help with heat loss by sweating and vasodilation of capillaries
Muscular system (muscles) Can help with heat production by working to create shivering
Cardiovascular system (heart and blood vessels) Helps heat distribution (spreading heat around the body)
Nervous system (brain and nerves) Co-ordinates the blood flow, heat production and heat loss

The second table names some systems that control the body’s fluid levels. This requires several organ systems to work together as well. For example:

System Function
Urinary system (kidneys, bladder, ureters) Removes water from the blood
Digestive system (stomach, liver, pancreas, gall bladder) Absorbs water in faeces to recycle it and reduce the amount that needs to be ingested
Integumentary system (skin) Loses water through perspiration
Cardiovascular system (heart and blood vessels) Moves water around the body
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Finding the Body’s Balance: Understanding Homeostasis

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