Oaks to arteries: The Physiology Core Concept of flow down gradients supports transfer of student reasoning

Abstract

The Physiology Core Concept of flow down gradients is a major concept in physiology as pressure gradients are the key driving force for the bulk flow of fluids in biology. However, students struggle to understand this principle is foundational to the mechanism governing bulk flow across diverse physiological systems (e.g., blood flow, phloem sap flow). In this study, we explore if bulk flow items that differ in context (i.e., taxa, amount of scientific terminology, living or non-living system) or which aspect of the pressure gradient is kept constant (i.e., starting pressure or pressure gradient) influences undergraduate students’ reasoning. We found item context did not impact the type of reasoning students used. However, students were more likely to use the Physiology Core Concept of “flow down [pressure] gradients” when the pressure gradient was kept constant and less likely to use this concept when the starting pressure was kept constant. We also investigated if item context or which aspect of the pressure gradient is kept constant impacted how consistent students were in the type of reasoning they used across two bulk flow items on the same homework. We found most students were consistent across item contexts (76%) and aspects of the pressure gradient kept constant (70%). Students who reasoned using “flow down gradients” on the first item were the most consistent (86, 89%) while students using “pressures indicate (but don’t cause) flow” were the least consistent (43, 34%). Students who are less consistent know pressure is somehow involved or indicative of fluid flow but do not have a firm grasp of the concept of a pressure gradient as the driving force for fluid flow. These findings are the first empirical evidence to support the claim that using Physiology Core Concept reasoning supports transfer of knowledge across different physiological systems. National Science Foundation award DUE 1661263 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.