What is the sodium-potassium pump, and what is its functional significance?
The Sodium Potassium pump is a large protein molecule , traversing the plasma membrane of the neuron.
The sodium potassium pump illustrates " active transport " since it moves sodium and potassium ions against their concentration gradients.
The part of the protein facing the cytoplasm has receptors for sodium ions. The other part facing the extra cellular environment has receptors for potassium ions.
The concentration of sodium and potassium ions ( across the plasma membrane ) are maintained at constant disequilibrium.
The sodium potassium pump moves 3 sodium ions inside the cell as against 2 potassium ions outside the cell.
This inequality of ion transfer produces a net effllux of positive charge. A polarised membrane with the inner surface slightly negative as compared to the outer surface is thus maintained.
This difference in charge generates electrical impulses, which lead to nerve impulses.