Endocrine system (CIE A-level biology)

This lesson describes the features of the endocrine system, focusing on the differing actions of peptide and steroid hormones at target cells. The detailed PowerPoint and accompanying resources have been primarily designed to cover point (1) of topic 15.1 of the CIE A-level biology specification but can also be used as a revision tool to check on their knowledge of the role of glucagon in the homeostatic control of blood glucose concentration from topic 14 whilst introducing transcription factors which will be covered in topic 16.

Students should have a base knowledge of the endocrine system from GCSE and topic 14 so this lesson has been planned to build on that knowledge and to add the detail needed at this level. The lesson begins by challenging this knowledge to check that they understand that endocrine glands secrete these hormones directly into the blood. Students will learn that most of the secreted hormones are peptide (or protein) hormones and a series of exam-style questions are used to challenge them on their recall of the structure of insulin as well as to apply their knowledge to questions about glucagon. Moving forwards, the students are reminded that hormones have target cells that have specific receptor sites on the surface of their membrane. The relationship between a peptide hormone as a first messenger and a second messenger on the inside of the cell is described to allow students to recall how the activation of cyclic AMP triggers a cascade of events on the inside of the cell. The rest of the lesson focuses on steroid hormones and specifically their ability to pass through the membrane of a cell and to bind to transcription factors, as exemplified by oestrogen.