The importance of the myelin sheath (CIE International A-level Biology)

This lesson has been written to cover the detail of specification point 15.1 (f) of the CIE International A-level Biology specification which states that students should be able to explain the importance of myelination. 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 is poorly explained by a lot of 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.

This lesson has been designed for students studying the CIE International A-level Biology course and the other part of this specification point which covers the refractory period was explained in the previous lesson on the transmission of the action potential