A task force of physiology educators from 25 Australian universities generated an Australia-wide consensus on seven core concepts for physiology curricula. One adopted core concept was "cell membrane," defined as "Cell membranes determine what substances enter or leave the cell and its organelles. They are essential for cell signaling, transport, and other cellular functions." This concept was unpacked by a team of 3 Australian physiology educators into 4 themes and 33 subthemes arranged in a hierarchical structure up to 5 levels deep. The four themes related to defining the cell membrane, cell membrane structure, transport across cell membranes, and cell membrane potentials. Subsequently, 22 physiology educators with a broad range of teaching experience reviewed and assessed the 37 themes and subthemes for importance for students to understand and the level of difficulty for students on a 5-point Likert scale. The majority (28) of items evaluated were rated as either Essential or Important. "Theme 2: cell membrane structure" was rated as less important than the other three themes. "Theme 4: membrane potential" was rated most difficult, while "theme 1: defining cell membranes" was rated as the easiest. The importance of cell membranes as a key aspect of biomedical education received strong support from Australian educators. The unpacking of the themes and subthemes within the cell membrane core concept provides guidance in the development of curricula and should facilitate better identification of the more challenging aspects within this core concept and help inform the time and resources required to support student learning. [This article was written with Task Force.]