Exploring Feedback and Control in the Human Body

• Human Regulation and Reproduction
• Further Education (Key Stage 5)

Exploring Feedback and Control in the Human Body

Learning Objective

Understand the concept of feedback and control in the human body, including positive and negative feedback loops and the roles of set point, receptors, coordinators, and effectors.

What do you know/remember about homeostasis?

Homeostasis

The maintenance of a constant internal environment 

within an organism. 

In order to survive, the body must keep its internal 

environment within certain parameters. 

Internal conditions that need to be maintained at a 

constant level are: 

• pH
• Temperature
• Salt concentration
• Blood glucose concentration

Feedback and Control

Feedback mechanisms maintain homeostasis by regulating internal conditions. Positive and negative feedback loops play essential roles.

Positive Feedback Loop

Positive feedback amplifies a response, leading away from the body's set point. It is less common in the human body.

This does not result in homeostasis, but is useful in
situations such as childbirth. 

A change in the condition of the body causes
effectors to amplify the change further away from
normal. 

Negative Feedback Loop

Negative feedback reverses a change and brings the body back to its set point. It is the primary mechanism in the human body.

Allows homeostasis to be achieved.

A change in one condition in the body causes 

effectors to restore the condition to its original 

level. 

Homeostasis: Temperature

Why is temperature important? 

The rate of metabolic reactions increases when the temperature is increased as molecules move faster = more enzyme collisions. 

So what happens if temperature gets too high or too low? 

Homeostasis: pH

Why is pH important?

Enzymes become denatured if it is too high or low. 

Metabolic reactions are fastest at their optimum pH, 

usually around pH7. 

Homeostasis: Glucose

Why is glucose important?

Too high - water potential of blood reduced to a point where water molecules diffuse out of cells into blood. 

Too low - Cells unable to carry out normal activities as there isn't enough glucose for respiration

Decreases

Decreases

Increases

Increases

Heating

Cooling

Now create a POSITIVE
feedback loop diagram

Homeostasis basics

Homeostasis basics

Homeostasis involves multiple feedback mechanisms for each thing being controlled. This is because having more than one mechanism gives more control over changes in your internal environment than just having one negative feedback mechanism.

Having multiple negative feedback mechanisms means you can actively increase or decrease a level so it returns to normal, e.g. you have feedback mechanisms to increase it. If you only had one negative feedback mechanism, all you could do would be turn it on or turn it off. You would only be able to actively change a level in one direction so it returns to normal. Only one negative feedback mechanism means a slower response and less control. 

Now create a NEGATIVE
feedback loop diagram

Quiz time! 

1. Which organ is involved in the negative feedback loop for blood glucose regulation?

1. Lung
2. Pancreas
3. Liver
4. Kidney

2. Why is a negative feedback loop essential for maintaining homeostasis?

1. Promotes rapid and drastic fluctuations in body functions
2. Triggers excessive hormone production
3. Prevents extreme changes in the internal environment
4. Enhances the effects of external stimuli

3. What happens in a negative feedback loop when body temperature rises?

1. Blood vessels constrict to conserve heat
2. Shivering is induced to generate heat
3. Digestive processes are accelerated
4. Sweating is triggered to cool the body

4. Which hormone is involved in the positive feedback loop during childbirth?

1. Oxytocin
2. Testosterone
3. Insulin
4. Adrenaline

5. What is the purpose of a positive feedback loop in homeostasis?

1. Inhibit the response to a stimulus
2. Amplify the response to a stimulus
3. Maintain a stable internal environment
4. Counteract the effects of a stimulus

Key Terms

Set point: The ideal level or range at which a physiological variable is supposed to be maintained.

Receptors: Receptors detect changes in the internal or external environment and send signals to the coordinator.

Coordinators: Coordinators receive and process information from receptors, sending signals to effectors to initiate a response.

Effectors: Effectors carry out the necessary actions to restore the body to its set point in response to signals from coordinators.

Note 3 things you learned in this lesson.

Have students enter three things they learned in this lesson. With this they can indicate their own learning efficiency of this lesson.

Write down 2 things you want to know more about.

Here, students enter two things they would like to know more about. This not only increases involvement, but also gives them more ownership.

Ask 1 question about something you haven't quite understood yet.

The students indicate here (in question form) with which part of the material they still have difficulty. For the teacher, this not only provides insight into the extent to which the students understand/master the material, but also a good starting point for the next lesson.