Misconceptions
Misconception 1: There are not any positive feedback systems in the human body
Students sometime assume there aren't any positive feedback systems in the body. Although the body largely employs negative feedback systems, positive feedback systems are present, and especially evident at the cellular level. The positive feedback mechanisms in the body tend to work under a broader negative feedback system to bring the body back to a homeostatic state.
For a detailed description of positive feedback systems, see feedback loops.
For a detailed description of positive feedback systems, see feedback loops.
Misconception 2: The human body can adapt to a wide range of climates
When learning about different organisms, sometimes students may point out humans can adapt to the cold weather in Canada and the warm tropic weather. It should be pointed out that the human body itself cannot tolerate the range of temperature that humans now reside in. Instead, it is the human creations that allowed us to adapt to our environmental conditions. In other words, it is only the clothes we wear and the furnace we use that allow us to adapt to the Canadian winters. The human body itself would have difficulty maintaining thermoregulation without these human inventions.
Misconception 3: The human body is static
A common misconception in homeostasis is the idea of a steady-state, or an implied static condition. Instead, the human body is constantly active, dynamic, and changing. It is constantly monitoring and responding to changes in conditions, whether it is external or internal. Therefore, the human body is said to be constantly in a dynamic equilibrium.
Misconception 4: External vs internal environments
Students often consider "environment" as the space surrounding us. It should be pointed out that the internal intestinal tracks from the mouth to the anus are technically external to the body. There is often a change in conditions in these spaces depending on what we ingest. Therefore, the human body must also maintain homeostasis in relation to this environment in addition to the external environment directly outside of our body.
Misconception 5: Negative feedback means less
Students sometimes will confuse positive and negative feedback meaning more or less. In the case of thermoregulation, students may assume positive feedback kicks in when the body is too warm, and negative feedback kicks in when the body is too cold. It is important to point out that negative feedback means less in relation to the stimulus, which can be hot or cold, strong or weak pH. In contrast, positive feedback means more in relation to the stimulus, such that the action results in a greater response.
For more common misconceptions in the homeostasis unit, see:
http://www.physiologyconcepts.org/teaching-learning/misconceptions/homeostasis-some-common-student-misconceptions/
http://www.physiologyconcepts.org/teaching-learning/misconceptions/homeostasis-some-common-student-misconceptions/