Controlling Heartbeat
How is the pulse rate controlled by the medulla and the adrenal glands? This simple classroom activity is worksheet based with an interactive whiteboard presentation. It will help students to make sense of the links between the medulla oblongata, the adrenal glands and the pacemaker of the heart. Students will understand the key differences between the nervous system and hormones, they will practice remembering the main biological concepts and create a sheet of revision notes.
Lesson Description
Guiding questions.png)
Could blood carry hormones from the adrenal gland to the heart?
Is it more likely that the brain controls heart rate?
What types of signals could be used to alter the rate of the heartbeat?
(Click the diagram if you would like to enlarge it)
Activity 1 - The myogenic cardiac cycle
Look at the diagram below and try to describe each step of how the blood flows through the heart.
Consider the electrical control of a single heart beat, and the role of the pacemaker while watching this short video.
Activity 2 - Summary explanations of the control of heart rate.
Read the bullet points on the worksheet which summarise the key details of the control of heart beat. Highlighting a few key words in each bullet point to help you remember it later.
Use these phrases as labels to annotate the diagram on the back of the sheet. 
Control of heart rate worksheet
Memorise the annotations as whole points.
Activity 3 - Think / Pair / Share
Think for a minute or two about what you would say if someone asked you to explain the diagram on the worksheet.
Run through the explanation in your head.
Pair with someone in the class for just five minutes and take turns to say your explanation out loud.
Offer suggestions of improvements to your partner. Ask for any clarifications you need and make a note of answers.
Share your explanation with the whole class - at the whiteboard if you are confident enough.
Answer these
IB style heart rate questions. Remember to use the new details which you have learnt.Extension - Video animation of a beating heart in the human body.
Teachers notes
This page can be projected on the whiteboard during the lesson.
The central part of the activity is a printable worksheet, there is a starter activity, an IB style question and a video animation which could be used as an extension.
Aims:
- The myogenic nature of heartbeat
- The control of heartbeat by the medulla (in the brain stem) using nerves
- The hormonal control of heartbeat by the adrenal glands
A possible lesson plan
Starter (10 minutes)
- Students get out notes and consider how the body might control the rate of heart beat.
- Plenary 'discussion' of the myogenic nature of the heart beat and a recap of the structure of the heart.
Main (30 minutes)
- Students read through the points on the worksheet, identify any points they don't understand and look for clarification of any confusion.
- Students label the diagram on the reverse side of the worksheet.
There are some suggestions for answers on the page Regulation of heart rate - model answers - Encourage the students to remember the labels as much as possible.
- Think Pair Share activity will help build student confidence in their understanding of the control of heartbeat
One or two students can share their explanations with the whole class.
End (20 minutes)
- Students attempt the IB style questions
Students could mark these using the model answer sheet. - There are some suggestions for answers on the page Control of heart beat IB style questions - model answers
Extension work
- Show the video to the whole class, or individual students can watch the final animation while others complete the questions.