Explore the membrane’s moving parts, follow different substances across it, and notice how a tiny boundary helps a cell stay connected to its surroundings. Select a structure in the diagram—or use the labels below it.
Tap or click a highlighted structure to learn what it does.
Each phospholipid has a water-attracting head and water-avoiding tails. In a watery environment, they arrange themselves into two layers, with the tails tucked inside.
Pick a substance to see how its size, charge and gradient shape its journey across the membrane.
Oxygen moves from higher to lower concentration. Because it is small and non-polar, it can dissolve in the hydrophobic interior of the membrane.
Watch the selected route.
The particle moves down its concentration gradient through the lipid bilayer.
Understanding a cell is one part of learning medicine. What questions might you ask before deciding what a membrane process means for a particular patient?