Heart's conduction system (OCR A-level PE)

This fully-resourced lesson describes the roles of the SAN, AVN, bundle of His and the Purkyne fibres in the heart’s conduction system. The engaging PowerPoint and accompanying resources have been designed to cover the final specification point of the “Cardiovascular system at rest” topic in unit 1.1.b of the OCR A-level PE specification

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 was introduced in the previous 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 full sequence of events in the conduction of the electrical impulse through the heart tissue, and there is a particular emphasis on the use of key terminology