Find your 9s with PLUS. Click the link to try for free https://www.freesciencelessons.co.uk/plus Teachers, to get PLUS for your school, email schools@freesciencelessons.co.uk In this video, we look at the roles of adrenaline and thyroxine and then explore how thyroxine levels are controlled by negative feedback. This video is based on the AQA spec. This video may be appropriate for iGCSE / O Level Biology. Please consult your specification. The Amazon link above is an affiliate link. This provides a small commission which helps to support freesciencelessons. The cost remains the same to you. If you prefer not to use this, you can search Amazon for the Freesciencelessons workbooks. Image credit: Beating heart By DrJanaOfficial - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=50477765 Music credit: Deliberate Thought by Kevin MacLeod is licensed under a Creative Commons Attribution licence (https://creativecommons.org/licenses/by/4.0/) Source: http://incompetech.com/music/royalty-free/?keywords=deliberate+thought Artist: http://incompetech.com/