Sodium-potassium pumps use ATP to export sodium and import potassium, maintaining ion gradients that support resting potentials; This exchange is central to nerve and muscle membrane recovery.
Coverage 2014–2019 · Updated 15 Jul 2026
The sodium–potassium pump uses ATP to move sodium out of a cell and potassium into it against their gradients, typically exchanging three sodium ions for two potassium ions per cycle.
ATP phosphorylation changes the pump’s shape so binding sites face alternate sides. Repeated cycles maintain unequal ion distributions that can later drive electrical signals or cotransport.
Track one cycle: three Na⁺ bind inside → ATP-powered shape change releases them outside → two K⁺ bind outside → reset releases K⁺ inside.
If the pump stops, diffusion gradually reduces the sodium and potassium gradients even though channels may still function.
The pump creates gradients; it is not the same as a channel that lets ions flow down those gradients.
This objective is assessed through structured response, commonly using Identify / Suggest / Analyse.
Identify / Suggest / Analyse
Build the answer around this relationship: Sodium-potassium pumps use ATP for active transport.
Reversing sodium and potassium movement across the membrane.
Representative question
Analyse the graph to obtain two conclusions about the concentration of sodium-potassium pumps.
1.
2.
The HL extension asks how membrane structure becomes dynamic cell behaviour. Fatty acid saturation and cholesterol tune fluidity. Fluid membranes form and fuse vesicles. Gated ion channels and sodium-potassium pumps create nerve-cell gradients and electrical responses. Sodium-dependent glucose cotransport uses a sodium gradient to move glucose indirectly against its gradient. Adhesion molecules organize tissues.
