Sensory, relay and motor neurones (Pearson Edexcel A-level Biology)

This fully-resourced lesson looks at the structures of the sensory, relay and motor neurones and explains how the presence of a myelin sheath increases the speed of conduction of an impulse. The engaging PowerPoint and accompanying resources have been designed to cover point 8.1 of the Pearson Edexcel A-level Biology A (Salters Nuffield) specification which states that students should be able to apply their understanding of the structures and functions of sensory, relay and motor neurones as well as the differences between myelinated and unmyelinated neurones. This lesson also covers 8.2 (i) as the students will be able to see how conduction along a motor neurone stimulates effectors to respond to a stimulus. The PowerPoint has been designed to contain a wide range of activities that are interspersed between understanding and prior knowledge checks that allow the students to assess their progress on the current topics as well as challenge their ability to make links to topics from earlier in the modules. Quiz competitions like SAY WHAT YOU SEE are used to introduce key terms in a fun and memorable way.

The students will be able to compare these neurones based on their function but also distinguish between them based on their structural features. Time is taken to look at the importance of the myelin sheath for the sensory and motor neurones. Students will be introduced to the need for the entry of ions to cause depolarisation and will learn that this is only possible at the nodes of Ranvier when there is a myelin sheath. Key terminology such as saltatory conduction is introduced and explained. The final task involves a comparison between the three neurones to check that the students have understood the structures and functions of the neurones.

Throughout the lesson, links are made to related topics such the organisation of the nervous system and students will be given additional knowledge such as the differences between somatic and autonomic motor neurones.