Homeostasis models
Because I want my students to have a thorough understanding of homeostasis before moving into their study of human physiology in our A&P course, I spend a LOT of time on this topic during the first week of class.
Because the concept of homeostasis is usually new to my students . . . and because I use three different analogies in an attempt to "get at" what homeostatic control really means . . . I provide them with some "extra" material on homeostasis online. I call this module a "mini lesson" and it's intended as a supplement to what they already get in the textbook and the lecture/discussion session.
My "homeostasis mini lesson" includes three analogies of how homeostasis maintains balance in the body:
1. The fishbowl model compares the human body to an aquarium. Health of the system requires stability of the fluid environments inside the tank. Various devices (like organs) operate to maintain that stability (of temperature, oxygen level, etc.).
- I bring a 2.5 gallon aquarium to the classroom and put a small stuffed fish in it. Then I ask, if this were a real fish, what would need for it to survive. Water. (I pretend to add water . . . I've tried using water and it's not worth the mess and time it takes.) Is that all? Nope, we need an air pump, heater, filter, buffers, automatic feeder, etc. Then I literally pack the aquarium with toy fish. What now? Very little water and a lot of balancing required, so I need a better filter, etc., and the system is still pretty fragile.
- We have some actual aquariums in our labs (facing the hallway) that I can point to as well.
- Instead of walking them through it in large group, try having students work out in small groups what would be needed for a successful aquarium . . . to maintain constant water quality. Then ask them what would be needed if we add a thousand more fish. Perhaps they can draw stick diagrams on poster paper.
- See below for FREE slides to use with this model
2. The engineered control system model uses a engineered thermostat to show students how automatic control sytems that maintain stability in a system are designed. This also helps introduce students to the essential terminology of homeostasis, which is borrowed from engineering.
- This model is illustrated in my textbooks (Chapter 1).
- Bring in an actual thermostatic control system (just as a prop). Perhaps give one to each group and ask them to draw a schematic of how it works, labeling disturbance, sensor, integrator, etc.
- See below for FREE slides with which to illustrate this model
3. The Wallenda model uses the famous family of circus wire-walkers to illustrate some additional concepts of balance in the body, such as how negative feedback helps keep us close to the set point.
- This model is explained in Chapter 1 of my brief manual:
Survival Guide For Anatomy And Physiology:
Tips, Techniques And Shortcuts
- See below for FREE slides and FREE videos with which to illustrate this model
Check out my Homeostasis Mini Lesson at my Lion Den website.
[NOTE: You are welcome to use the information in your own course by linking to my Mini Lesson. You may also use my material in your handouts (not for general publication) if you agree to cite the source as "Copyright Kevin Patton, lionden.com"]
Free Slides and Videos
Here are some FREE slides related to homeostasis that you can use in your course:
You can get my whole collection of supplemental A&P slides in an editable format. Visit Lion Den Slide Collection for details.
Don't know who the Wallendas are? Check out these video clips!
Here's a clip showing the great Karl Wallenda and the Great Wallendas in 1962.
Note the appearance "11-year old Tino" who is currently the patriarch of the family.
Here's a clip of today's act, known as The Flying Wallendas.
Tino is in the very last "anchor" position in the pyramid.
Here's a clip of the tragic fall to the death of Karl Wallenda.
I use this event in my analogy to underscore that death is always caused by a failure to maintain (homeostatic) balance. And as strong advice in choosing career paths wisely.
Here's another example of what can go wrong when balance is lost.
[Go to The A&P Professor YouTube page to learn how to embed any of these videos in your PowerPoint or webpage . . . or simply link to it from your own email or webpage.]
Related blog entries
- Homeostasis mini lesson
- Engineer's view of biological systems
