Positive and Negative Feedback

In this lesson, you will learn about negative and positive feedback as a means of maintaining homeostasis in the body. Specifically, you will learn about:

1. Overview of Homeostasis
2. Negative Feedback
3. Positive Feedback

1. Overview of Homeostasis

Homeostasis is the maintenance of our internal environment.That environment is maintained by either negative or positive feedback.

• Homeostasis
• The maintenance of the body’s internal environment.
• Negative Feedback
• A mechanism in which a change in the body is detected and then reversed to maintain homeostasis.
• Positive Feedback
• A mechanism in which a change in the body is detected and then intensified.

2. Negative Feedback

Negative feedback is the most common type of feedback that we experience. Negative feedback will reverse a detected change.

Conditions in your extracellular fluid might experience changes at times. Maybe the pH changes, the temperature changes, or the chemical makeup changes. Sensory receptors will detect that change. The change will then be reversed in order to maintain homeostasis, as cells need to be in an environment that's relatively constant.

If the pH or temperature gets too high or too low, cells aren't going to be able to function properly, meaning that other body mechanisms aren't going to function properly either. So it's really important that homeostasis is maintained.

• Sensory Receptor
• Receptors that detect a stimulus or change in the body.
• Integrator
• The main integrator in the body is the brain. The integrator receives signals from sensory receptors and determines an appropriate response.
• Effectors
• Glands or muscles that carry out the response as designated by the integrator.
• Stimulus
• A stimulus is a change in the body.

Take a look at the diagram below to see how negative feedback works to maintain homeostasis.

First, your body will experience some sort of stimulus. Let's say you walk outside today, and it's really hot. 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 will send that information to effectors, which are glands or muscles. Those effectors will then carry out the response.

There are different mechanisms in order to cool down your body temperature, and vasodilation is one mechanism. Vasodilation is when your blood vessels widen in order to expel excess heat. Effector will work to carry out responses such as vasodilation and sweating. When you sweat, the fluids that you sweat out will be evaporated off your body, allowing your body temperature to cool. You might experience heavy breathing when you're really hot, and your muscle activity will also be reduced. These are all ways that your body temperature could be lowered.

From there, the response would be that your body temperature lowers, meaning that the change you first experienced has been reversed.

3. Positive Feedback

Positive feedback is more rare in the body, and it doesn't have a huge effect on homeostasis. Again, when you're talking about homeostasis, you're talking about the maintenance of our extracellular fluids.

Positive feedback will detect a change, and rather than reversing it, it will actually intensify it.

IN CONTEXT

A common example is childbirth. In childbirth, the fetus will exude pressure on the mother's uterus. The uterus will then exude pressure on the fetus back and forth. This will keep intensifying until, finally, the fetus is expelled. Rather than that change reversing, it is actually being intensified.

This lesson has been an overview of negative and positive feedback and the maintenance of homeostasis in the body.

Keep up the learning and have a great day!