laying volleyball is hard work, especially in the hot sun. The players’ bodies were using their mitochondria to burn sugar for fuel and giving off heat in the process. Between that and the heat they absorbed from the sun, their body temperatures began to rise. That rise in temperature triggered their bodies to perspire, because as perspiration evaporates, it carries away heat, thereby cooling the body. Of course, some people found another way to cool off: swimming in the creek behind Farmer Melanie’s field.
Homeostasis – Maintaining Balance
Consider just a few of the things that are happening here:
Out of that list, there are several of these “reactions”
that are rather interesting:
increase in body temperature → increased sweating → decreased body temperature
decrease in body temperature → shivering → increase in body temperature
and, slightly more complex,
decrease in body fluids → increase in thirst → increase in fluid consumption → increase in body fluids
Notice that in each case, a change in a particular body condition triggers a reaction which, in turn, brings about the opposite change in the body condition which triggered it. These are all examples of negative feedback loops, processes in which the “feedback” sends the process in the opposite direction from that in which it was initially headed. Our bodies use many types of negative feedback loops to maintain homeostasis, which is the ability of an animal’s body to maintain a constant internal environment.
There are many other examples of negative feedback loops in the world around us, many of which aren’t even biological. Consider what happens when you flush a toilet.
Links to Related Information on Our Web Server
The following Web pages contain information related to
how our bodies maintain homeostasis.
Examples of Homeostasis
In this project, you will examine some negative feedback loops at work in your everyday life. Assuming your toilet is made like msmy here in America, the filling mechanism in its water tank is a good example of a negative feedback loop. The grading criteria for this assignment are given below, and you should also refer to those as you work on the assignment. A total of 12 points is possible.
|2||—||The student was very observant and took excellent notes on the functioning of the toilet|
|1||—||The student observed and took adequate notes on the functioning of the toilet|
|0||—||The student’s notes are sketchy and suggest that (s)he did not pay much attention to how the toilet works|
|2||—||It is evident that the student clearly and thoroughly grasped the concept of homeostasis and its role in maintaining the toilet’s water level|
|1||—||The student partially understood the process of homeostasis in maintaining the water level|
|0||—||The student gave little or no indication of comprehension of the relationships and processes involved in maintaining the water level|
|2||—||The student correctly identified and took excellent notes on a biological negative feedback loop|
|1||—||The student correctly identified and took adequate notes on a biological negative feedback loop|
|0||—||Either the process which the student observed was not a biological process or was not a negative feedback loop, and/or the student’s notes were too sketchy|
|2||—||The student correctly identified and took excellent notes on a non-biological negative feedback loop|
|1||—||The student correctly identified and took adequate notes on a non-biological negative feedback loop|
|0||—||Either the process which the student observed was a biological process or was not a negative feedback loop, and/or the student’s notes were too sketchy|
|2||—||The student, obviously, went beyond the minimum requirements of the assignment|
|1||—||The student adequately completed the assignment|
|0||—||The student completed considerably less of the assignment than what was required|
|2||—||It is evident that the student used much insight, thoughtfulness, and critical thinking when completing this assignment|
|1||—||The student adequately thought about the assignment – there was, perhaps, a bit of “fuzzy thinking” in a couple places|
|0||—||The assignment gives the appearance of being “slapped together” just to get it done, with little evidence of thoughtfulness|