Saltatory conduction (Edexcel Int. A-level Biology)

This lesson describes the role of myelination in saltatory conduction. The PowerPoint and accompanying worksheet have been designed to cover point 8.5 of the Edexcel International A-level Biology specification and includes constant references to the earlier lessons on the structure of neurones and the conduction of an action potential along an axon.

A wide range of activities have been written into this resource to maintain the motivation of the students whilst ensuring that the detail is covered in depth. Interspersed with the activities are understanding checks and prior knowledge checks to allow the students to not only assess their understanding of the current topic but also challenge themselves to make links to earlier topics such as the movement of ions across membranes and biological molecules. Time at the end of the lesson is also given to future knowledge such as the involvement of autonomic motor neurones in the stimulation of involuntary muscles.

Over the course of the lesson, students consider the structure of the myelin sheath and specifically how the insulation is not complete all the way along which leaves gaps known as the nodes of Ranvier which allow the entry and exit of ions. Saltatory conduction tends to be poorly explained by students so time is taken to look at the way that the action potential jumps between the nodes and this is explained further by reference to local currents. The rest of the lesson focuses on the other two factors which are axon diameter and temperature and students are challenged to discover these two by focusing on the vampire squid.