Acknowledgements
This free course was written by Vikki Haley and Karen New. It was first published in September 2025.
This OpenLearn course is an adapted extract from the Open University course SK190 Human biology: a body in balance [Tip: hold Ctrl and click a link to open it in a new tab. (Hide tip)] .
Except for third party materials and otherwise stated (see terms and conditions), this content is made available under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 Licence.
The material acknowledged below is Proprietary and used under licence (not subject to Creative Commons Licence). Grateful acknowledgement is made to the following sources for permission to reproduce material in this free course:
Images
Course image: JAYK-ART / Shutterstock
Figure 7: ScienceDirect
Figure 9: Nick Youngson, https://pix4free.org/photo/31273/prescription-drugs.html, Image is under a Creative Commons Share Alike (CC BY-SA 3.0) Licence, https://creativecommons.org/licenses/by-sa/3.0/
Figure 31: Belova59 / Pixabay
Figure 32: adapted from Figure 1(c) of Anthony et al. (2022), Cell Reports, 39(2): 110649. DOI: 10.1016/j.celrep.2022.110649
Figure 33: Ozdemir, T. (2018) ‘Design and construction of therapeutic bacterial sensors in Escherichia coli Nissle 1917’, Doctoral thesis (Ph.D), UCL (University College London)
Video
Video 1: Overview of body systems affected by the acute stress response. sk299_T12_Video1.1_Slidecast_1_Mixed race teenage couple watching a movie at home, LaraBelova / Getty Images; sk299_T12_Video1.1_Slidecast_4_The brain, Trifonov_Evgeniy / Getty Images; sk299_T12_Video1.1_Slidecast_6_Immune System Concept, wildpixel / Getty Images; sk299_T12_Video1.1_Slidecast_3_Cuisine Culinary Buffet Dinner Catering Dining Food Celebration, _jure / Getty Images; sk299_T12_Video1.1_Slidecast_2_Beating heart, 3DME PTY LTD / Science Photo Library; sk299_T12_Video1.1_Slidecast_5_There are decreases in reproductive hormone production, Claus Lunau/Science Photo Library; sk299_T12_Video1.1_Slidecast_5_Female fighter with injured knee in gym, Dean Mitchell / Getty Images.
Video 2: TED-Ed, Summary of epigenetics, Licensed under the Creative Commons Attribution-Noncommercial-NoDerivatives Licence http://creativecommons.org/licenses/by-nc-nd/4.0/
Every effort has been made to contact copyright owners. If any have been inadvertently overlooked, the publishers will be pleased to make the necessary arrangements at the first opportunity.
Don’t miss out
If reading this text has inspired you to learn more, you may be interested in joining the millions of people who discover our free learning resources and qualifications by visiting The Open University – www.open.edu/ openlearn/ free-courses.