Potassium channels
Potassium Channels
Potassium channels (pronunciation: pəˈtæsiəm ˈtʃænəlz) are the most widely distributed type of ion channel and are found in virtually all living organisms. They form potassium-selective pores that span cell membranes. Furthermore, potassium channels are found in most cell types and control a wide variety of cell functions.
Etymology
The term "Potassium" is derived from the word "potash", which refers to plant ashes soaked in water in a pot, which was the primary means of manufacturing the product before the industrial era. The word "channel" in this context is derived from the Latin word "canalis" meaning a pipe, tube, or gutter.
Function
Potassium channels function to conduct potassium ions down their electrochemical gradient, doing so both rapidly (up to the diffusion rate of K+ ions in free water) and selectively (excluding, most notably, sodium despite the chemical similarities of Na+ and K+). They are integral in shaping the action potential.
Types of Potassium Channels
There are four main types of potassium channels:
- Voltage-gated potassium channels: These channels open or close in response to the voltage difference across the membrane.
- Inwardly rectifying potassium channels: These channels allow more current to flow into the cell than out of it.
- Tandem pore domain potassium channels: These channels have two pore-forming P domains.
- Calcium-activated potassium channels: These channels are activated by the presence of calcium ions or other signalling molecules.
Related Terms
External links
- Medical encyclopedia article on Potassium channels
- Wikipedia's article - Potassium channels
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