The SAN and AVN (Edexcel A-level PE)

This fully-resourced lesson describes the roles of the sinoatrial node (SAN) and the atrioventricular node (AVN) in the control of blood flow through the heart. The engaging PowerPoint and accompanying resources have been designed to cover the second part of point 1.2.5 as detailed in the Edexcel A-level PE specification and also includes the roles of the bundle of His and Purkyne fibres to enable students to get a full understanding.

The lesson begins with the introduction of the SAN as the natural pacemaker and then time is given to study each step of the conduction of the impulse as it spreads away from this node in a wave of excitation. The lesson has been written to make clear links to the cardiac cycle (which is covered in an upcoming lesson) and to the structure of the heart and students are challenged on their knowledge of this system. Moving forwards, students are encouraged to consider why a delay would occur at the AVN and then they will learn that the impulse is conducted along the bundle of His to the apex before being conducted on the Purkyne fibres so that the contraction of the ventricles can happen from the bottom upwards. The final task of the lesson challenges the students to describe the conducting tissue, with an emphasis on the use of key terminology