Feedback & control of body functions (2025)
In this series of activities, the feedback mechanisms that control heart rate and breathing rate, using sensory inputs from baroreceptors and chemoreceptors, are explored first. Then the voluntary and involuntary control of peristalsis in the digestive system is looked at.
Lesson description
Starting questions
How do we change our breathing rate and heart rate to cope with the demands of exercising?
What factors in the body might be detected in order to stimulate these changes?
Activity 1 - Baroreceptors & chemoreceptors
Watch the video below to learn about the baroreceptors and chemoreceptors involved in controlling the heart and breathing rate. Complete the short comprehension questions after.
Baroreceptors and chemoreceptors video
Questions
- Where are the baroreceptors located?
.................................................................................... - What do baroreceptors detect?
.................................................................................... - Where are the chemoreceptors located?
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.................................................................................... - What do chemoreceptors detect?
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.................................................................................... - Where do the baroreceptors and chemoreceptors send signals to when they detect stimuli?
.................................................................................... - Suggest how increased carbon dioxide in the blood after respiration during exercise results in a change in the pH of the blood.
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Click on the eye icon below to reveal the suggested answers.
Questions
- Where are the baroreceptors located?
Aortic arch and the carotid sinus.
- What do baroreceptors detect?
A change in blood pressure (they stretch when blood pressure is high - mechanoreceptors).
- Where are the chemoreceptors located?
Aortic arch and the carotid sinus.
There are also some central ones in the brainstem (medulla).
- What do chemoreceptors detect?
Changes in blood pH.
Concentrations of CO2.
Concentrations of O2.
- Where do the baroreceptors and chemoreceptors send signals to when they detect stimuli?
The medulla (specifically, the cardiovascular centre of the medulla)
- Suggest how increased carbon dioxide in the blood after respiration during exercise results in a change in the pH of the blood.
The carbon dioxide dissolves in the blood to form carbonic acid.
When the H+ ions dissociate from the carbonic acid, this causes the blood pH to decrease slightly.
Activity 2 - Control of heart rate & breathing rate
The video below shows how the baroceptors detect and bring about changes in blood pressure.
Use the information to complete the worksheet.
Control of heart rate and breathing rate worksheet
Activity 3 - Control of peristalsis
Read the short comprehension about the enteric nervous system and the role it plays in control of peristalsis and coordination of the passage of material through the gut.
Use the information to answer the multiple choice questions at the end.
The control of peristalsis in the digestive system worksheet
Teacher only boxActivity 1 - This is a short activity to introduce the receptors involved in the control of heart and breathing rate. The answers have been simplified to be in line with the specification.
Activity 2 - The video can be used to show the processes involved in blood pressure regulation. Then the worksheet goes into more detail about the processes involved in the regulation of heart and breathing rate.
Activity 3 - This short comprehension and multiple choice question activity introduces the enteric nervous system and it's role in the involuntary control of peristalsis.