A New Approach to Teaching Membrane Potentials

Abstract

Many of the students in my beginning biology classes have limited or no previous biology background. Frequently, many of these students are nonscience majors, with the majority of them pursuing business-related majors. One of the most important challenges I face as a biology teacher is using real-world examples to explain a biological principle. Taking material from a biology textbook and presenting it in terms easily grasped by beginning students is difficult. The use of analogies frequently helps to simplify the explanation of difficult concepts. One principle that beginning students often find particularly vexing is the concept of transmembrane potentials, especially the conditions that contribute to the resting membrane potential and the action potential. These concepts of transmembrane potentials are the foundation upon which any subsequent discussion of neurophysiology and nervous system function will be based. I approach the transmembrane potential from the viewpoint of a checking account. This approach allows me to introduce this concept without intimidating the students. I use the same analogy, with different levels of complexity, in my freshmanlevel and junior-level courses. Nearly everyone has a checking account and is at least somewhat familiar with balancing it. Thus, to explain membrane potentials to nonscience majors, I build an analogy between maintaining a checking account and maintaining a cell's homeostasis. Since by convention the transmembrane potential is measured using the inside of the cell as the reference point, the inside of a cell is portrayed as a checking account. A semipermeable plasma