Homeostasis: Maintaining a Constant Internal Environment
Next Generation: HS.LS1.3 NGSS

Homeostasis: Maintaining a Constant Internal Environment


This lesson will examine various homeostatic controls that allow the body to maintain a constant internal environment.

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Source: Video and Images Created by Amanda Soderlind

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Welcome to this lesson today on homeostasis. Today we will be discussing how homeostasis allows your body to maintain a constant internal environment. So homeostasis is basically the maintenance of a constant internal environment. And this constant internal environment is maintained in several ways.

So changes in your extracellular fluids, which is the fluids outside of your cells, need to be stabilized so cells can function properly. So cells function best when they're in a certain type of environment. So the pH, the concentration of solutes, the temperature, et cetera, all this needs to be maintained fairly stable. So if there's some sort of change in this extracellular fluid, your body will act to try and reverse that change to try to maintain homeostasis.

So homeostasis maintains the makeup and volume of extracellular fluids. So cells, tissues, organs, and organ systems all function together in order to try and maintain homeostasis. So within our body we have sensors, integrators, and effectors that will interact together to help maintain homeostasis. So we're going to take a look at an example of sensors, integrators and effectors right now.

So if we take a look at this diagram right here, it'll help us understand this concept a little bit better. So sensors or sensory receptors are cells that sense a stimulus or a change. And they're found throughout our body. So I just drew the eye here as a visual. But we actually have various different types of sensory receptors all throughout our body that detect changes or detect a stimulus.

And then the integrator is another important factor here, which is our brain. So the brain is the main integrator in our body. And then effectors are either muscle or gland cells. So these will all work together in order to maintain homeostasis.

So for example, sensory receptors in your body will detect some sort of stimulus or some sort of change within your body. That information will then be sent to the integrator, which is your brain. And your brain will gather that info, process it. And then it will determine an appropriate response that needs to occur for homeostasis to be maintained. And then whatever response it decides is appropriate, it will send that information to your effectors, which are your gland or muscle cells, to carry out that response to maintain homeostasis.

So to give you a more concrete example here, throughout your skin you have thermoreceptors, which are a type of sensory receptor that detect changes in temperature. So let's say those thermoreceptors throughout your skin determine that it is too cold and your body temperature starts to drop.

Your brain will then receive that information that your body temperature is dropping, because as I mentioned, in order for cells to function optimally, they have to be in certain conditions. And if the temperature's too low, your body and your organs are not going to function as well as they would otherwise. So we need to maintain this constant internal environment.

So when the temperature drops, that information is picked up by sensory receptors. That information is then transferred to your brain. Your brain will then determine an appropriate response in order to help maintain your internal body temperature. So if you're too cold, one of the things that your brain might determine is an appropriate response is that you will shiver. That's not the only thing that'll happen. But that's one example of something that will happen.

So that information will then be sent to your muscle cells. And you will begin to shiver, which produces body heat. So that's an example of how these will work together in order to maintain homeostasis.

So negative and positive feedback are two mechanisms of control. These are two ways that homeostasis is maintained. Negative feedback is the most common.

Positive feedback does occur in your body. It doesn't have a massive role in homeostasis. But negative feedback is one of the main mechanisms of maintaining homeostasis. And if you're more interested about that, you can do a little bit more research on what positive and negative feedback are. But for this lesson, you just need to know that they're both mechanisms of control in order to help maintain homeostasis.

So this lesson has been an overview on homeostasis.

  • Homeostasis

    The maintenance of  a constant internal environment.

  • Sensory Receptors

    Receptors located throughout your body that detect a stimulus.

  • Integrator

    Your brain is the integrator that senses a stimulus and determines an appropriate response.

  • Effectors

    Muscles or glands that carry out the response designated by the integrator.

  • Negative Feedback

    A feedback mechanism that maintains homeostasis by reversing the change.

  • ​Positive Feedback

    A feedback mechanism that intensifies a detected change.