Potassium and sodium ions act as power generators inside the cells of your body. Neurons are cells located throughout your nervous system. They communicate information to perform important tasks such as regulating your body temperature or flexing muscles. For instance, if you want to move your fingers, your brain transmits a message to the muscles in your hand. Neurons transmit that message. Neurons use ions to communicate. Ions are electrically charged chemicals. Potassium and sodium are two of the most important ions in your nervous system.
Pure water does not conduct electricity. Potassium, sodium and other electrolytes dissolve in water and help carry an electrical charge. The cells in your body need electrolytes to transport and maintain electrical impulses. The sodium-potassium pump describes a mechanism in which sodium and potassium ions move in and out of your cells. Each time this happens, an electrical charge is produced. The sodium-potassium pump also responds to power requests from your nervous system. Proper electrolyte balance is important for your blood, hydration and helps maintain other vital body functions.
The sodium-potassium pump carefully selects which ions to allow in or out of cells. This maintains the electrical charge. At any given time, three sodium ions are allowed inside a cell. When drawing in sodium ions, the cell is positioned to attract ions shaped like sodium ions. It then reverses position, releases the sodium ions and draws in two potassium ions. In "Biological Psychology," James W. Kalat writes that the result of this process is that sodium ions are more concentrated outside of your cell membranes while potassium ions are more concentrated inside cell membranes.
The resting potential of a cell is the amount of energy available when a cell is at rest. Your body expends a great deal of energy operating the sodium-potassium pump. The resulting resting potential is what allows for rapid responses to requests from your brain. In "Biological Psychology," Kalat compares resting potential to a bow and arrow that is poised and ready to fire. An archer pulls on the bow and waits for a target just as the sodium-potassium pump is primed and ready for action.
When a simulated neuron makes a request, sodium ions shoot like arrows into your cells, creating an explosion of energy. Sodium ions move first because of the uneven concentration between sodium and potassium ions. It takes a little longer for potassium ions to move outside of your cells. When they do, the in and out flow of potassium and sodium ions creates polarization and reverse polarization. This is the action potential. Eventually, the ions settle down and return to resting potential.
- Protein Data Bank; Sodium-Potassium Pump; David Goodsell; October 2009
- McKinley O'Loughlin Human Anatomy; Animation: How the Sodium Potassium Pump Works; 2006
- "Biological Psychology"; James W. Kalat, Ph.D.; 2008