Students will compare negative feedback loops in dogs and humans, related to body temperature.
Students will define and compare negative and positive feedback loops in humans and dogs.
Next Generation Science Standards
Plan and conduct an investigation to provide evidence that feedback mechanisms maintain homeostasis. HS-LS1-3
Disciplinary Core Idea L S1.A: Structure and Function
Feedback mechanisms maintain a living system’s internal conditions within certain limits and mediate behaviors, allowing it to remain alive and functional even as external conditions change within some range. Feedback mechanisms can encourage (through positive feedback) or discourage (negative feedback) what is going on inside the living system.
Computer(s) with internet access (at teacher discretion, students may use internet-enabled devices or teacher may display the video from the classroom computer)
Interactive Model of Human Homeostasis from explorelearning.com (optional). This website is by subscription only, but you can get a free 30 day subscription. If your school has a subscription, this is an excellent tool for allowing students to explore homestasis and how negative feedback loops work in humans to regulate body temperature. (See Resources)
- Assign students partners. Ask them to look at each other’s pupils. Then turn off the lights for about a minute and ask students to close their eyes. Tell students to look again when you turn the lights on.
- Ask students to describe what happens to their partner’s pupils when the light comes back on.
- Have students offer explanations for why this happens (Your pupils dilate when the lights go out to let as much light in as possible. When the lights come back on your pupils contract to reduce the amount of light coming in. Too much light can damage the optic nerve, but not enough light means we can’t see well.)
- Review or introduce the terms stimulus and response and have students describe how these terms relate to what they just observed with their partner’s pupils. E.g. the reduction of light is a stimulus; the eye’s response is to dilate the pupil, and when the lights come back on the increase in light stimulates the pupil to constrict.
Explicit Instruction/Teacher Modeling
- Show students the video Homeostasis and Negative/Positive Feedback from this youtube link. https://youtu.be/Iz0Q9nTZCw4
- Pause at minute 3:18 to review and discuss the definition of a negative feedback loop and how it relates to body temperature.
- Continue viewing to hear about blood glucose and homeostasis as well as the human birth process as an example of a positive feedback loop.
- Have students read the article Do Dogs Sweat, either through their own internet-enabled devices, or a printed copy. Depending on your group, you may choose to have students read this independently, in pairs, or as a whole class.
- Pass out the “Canine and Human Homeostasis” sheet.
- Instruct students to complete the sheet. Students may find it useful to refer back to the video and article.
Review and Closing
- Review the answers with students. See answer sheet.
Rodolfo, Kelvin. (n.d.). What is Homeostasis? Retrieved from https://www.scientificamerican.com/article/what-is-homeostasis/
Amoeba Sisters. (2017, September 7). Homeostasis and Negative/Positive Feedback. Retrieved from https://youtu.be/Iz0Q9nTZCw4
Burke, Anna. (2019, April 18). Do Dogs Sweat? Retrieved from https://www.akc.org/expert-advice/health/do-dogs-sweat/