Introduction
Start with the big picture
The lesson connects membrane composition—phospholipids, cholesterol, and proteins—to selective permeability and the fluid-mosaic model. It introduces passive and facilitated diffusion, ATP-driven primary transport, and secondary transport coupled to ion gradients, alongside osmosis and the distinction between osmolarity and tonicity. Ion gradients also underpin membrane potentials: the Nernst equation describes an ion’s equilibrium potential, while the Goldman equation relates to resting potential, which is strongly influenced by potassium leak conductance. The topic further previews gated ion channels, endocytosis and exocytosis, signal transduction, homeostasis, and cell death. Together, these concepts show how membrane structure and transport support cellular balance and function.
What you'll learn
- Describe the plasma membrane’s main components and the fluid-mosaic model.
- Distinguish passive diffusion, facilitated diffusion, and active transport.
- Explain how osmosis, osmolarity, and tonicity relate to cell volume.
- Relate ion gradients and channel activity to membrane potentials.
- Identify the roles of bulk transport and membrane signaling.
Continue your study
Work through the complete notes and reinforce the topic with the study tools available in the full lesson.
