Lesson overview

In this lesson students continue their exploration of the circulatory system, locating the SA and AV nodes and explaining how atrial contraction is controlled / triggered. Students go on to describe the steps in the cardiac cycle.

Learning outcomes

• To be able to identify the location of the SA (sinoatrial) Node, AV (atrioventricular) node, Purkinje fibres, and bundle of His
• To be able to describe the steps in the cardiac cycle

Lesson steps

1. Introduction (15 mins)
   Ask what makes your heart beat and your heart muscle contract? Explain that muscle contraction is controlled by nervous (electrical) impulses and that they will be exploring this in more detail in the expedition.
   Students watch a 3D animated video that explains how the heart works in general with some information about the control of heart beats.
   Explain mission for the expedition: to explore electrical control of the heartbeat. Outline questions that students will answer during expedition: Where and what is the SA node? Where and what is the AV node? How is atrial contraction controlled / triggered? How is ventricular contraction controlled / triggered?
   
2. Expedition (15 mins)
   Lead expedition, with a focus on the final scene, Heart Nodes.
   Students explore the scene and read all accompanying information about the points of interest answers to the following questions: Where and what is the SA node? Where and what is the AV node? How is atrial contraction controlled / triggered? How is ventricular contraction controlled / triggered?
   Students use the Student Sheet, found in the Lesson resources section to start completing the diagram and produce a flow chart to show what happens when the heart beats.
3. Activity one (15 mins)
   Students watch How The Heart Works - 3D Animation, to add more labels to their diagram. Students answer the questions: How is the contraction and synchronisation of heart muscle controlled? What happens to heart / pulse rate during exercise and why? Discuss answers with the class.
4. Activity two (15 mins)
   Students develop an experiment into the effect of exercise on heart rate (they can use pulsometers, stethoscopes or their fingers to count their pulse/heart rate).
   Remind students that when writing conclusions pupils must use vocabulary from this expedition to explain why and how their pulse rate has changed.
5. Extension
   Students research how to interpret an ECG and what it measures perhaps with this video from the expedition prep section.
   Students investigate what happens when the electrical impulses “go wrong” to prepare for the next lesson.
   

England

Key Stage 3/4 Science

• The relationship between the structure and functions of the human circulatory system