Positive and Negative Feedback

Video Transcription

In this lesson today, we will discuss negative and positive feedback as a means of maintaining homeostasis in our body. So homeostasis is just that maintenance of our internal environment. And the internal environment is maintained by either negative or sometimes positive feedback.

So we're going to start by discussing what negative feedback is, and how that contributes to maintaining homeostasis. So negative feedback is the most common type of feedback that we experience. And negative feedback will reverse a detected change.

So conditions in your extra cellular fluid might experience some sort of change. Maybe the pH changes, the temperature changes, the chemical makeup changes, and sensory receptors will detect that change. And then that change will be reversed in order to maintain homeostasis. So cells need to be in an environment that's relatively constant.

If the pH or temperature gets too high or too low, the cells aren't going to be able to function properly, and then other body mechanisms aren't going to function properly as well. So it's really important that homeostasis is maintained. So we're going to take a look, here, at this diagram, and just give an example of how negative feedback works to maintain homeostasis.

So first, your body will experience some sort of stimulus. So let's say you walk outside today, and it's really hot outside. So the stimulus would be the heat that you feel. You start to get really hot from being outside. Sensory receptors in your skin will detect that heat and send the information to the main integrator in your body, which is the brain.

Your brain will, then, interpret what needs to happen in order to lower your body temperature. And then it'll send that information to effectors, which are glands or muscles. And those effectors will then carry out the response.

So let's say your brain gets the information that your body's getting too hot. There's a few ways that your body can cool down. There's different mechanisms in order to cool down your body temperature.

Vasodilation is one example. Vasodilation is when your blood vessels will widen, and they do this in order to expel access heat. So effectors, muscles or glands, will work to carry out these responses such as vasodilation, sweating.

So when you sweat, the fluids that you sweat out will be evaporated off your body. And then by being evaporate off your body, it allows your body temperature to cool. You might experience heavy breathing when you really hot, and when you're really hot, your muscle activity will also be reduced. So these are all ways that your body temperature could be lowered.

And then from there, our response would be that our body temperature lowers. So you'll notice how the change, that we first experienced, is reversed. Here's another little example, just to show you how that change is reversed.

So back to kind of the example we just talked about, your body temperature rises, you sweat, and your body temperature drops. So the change that we first experienced, the rise in body temperature, is reverse by us sweating. And like I said, sweating isn't the only way our body temperature can be reversed, but it's just one of the examples.

So let's discuss a little bit about positive feedback. Positive feedback is more rare in our body, and it doesn't have a huge effect on homeostasis. When we're talking about homeostasis, we're talking about the maintenance of our extracellular fluids.

So positive feedback doesn't have a huge role in this, but it's also important just to kind of understand what positive feedback is, and what role it does have in our body. So positive feedback will detect a change, and rather than reversing it, it will actually intensify it. So a common example is childbirth.

So in childbirth, the fetus in the mother will exude pressure on the uterus. And the uterus will, then, exude pressure on the fetus back and forth. This will keep intensifying until, finally, the fetus is expelled.

So rather than that change reversing, it is actually being intensified. So this lesson has been an overview on negative and positive feedback and the maintenance of homeostasis in our body.