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Ion channels are located within the membrane of all excitable cells, [3] and of many intracellular organelles. They are often described as narrow, water-filled tunnels that allow only ions of a certain size and/or charge to pass through. This characteristic is called selective permeability.
The Goldman–Hodgkin–Katz flux equation (or GHK flux equation or GHK current density equation) describes the ionic flux across a cell membrane as a function of the transmembrane potential and the concentrations of the ion inside and outside of the cell. Since both the voltage and the concentration gradients influence the movement of ions ...
Voltage-gated ion channels are a class of transmembrane proteins that form ion channels that are activated by changes in a cell's electrical membrane potential near the channel. The membrane potential alters the conformation of the channel proteins, regulating their opening and closing. Cell membranes are generally impermeable to ions, thus ...
Potassium channels function to conduct potassium ions down their electrochemical gradient, doing so both rapidly (up to the diffusion rate of K + ions in bulk water) and selectively (excluding, most notably, sodium despite the sub-angstrom difference in ionic radius). [4] Biologically, these channels act to set or reset the resting potential in ...
Bertil Hille pioneered the concept of ion channels as membrane proteins forming gated aqueous pores (with Clay Armstrong). [6] [7] He showed that Na+ and K+ channels of axons could be distinguished by drugs such as tetrodotoxin and tetraethylammonium ion, and that their ionic selectivity can be understood by limiting pore size, the selectivity filter, and by movements of ions through a series ...
Gating (electrophysiology) An animated representation of the molecular structure of a simple ion channel. In electrophysiology, the term gating refers to the opening (activation) or closing (by deactivation or inactivation) of ion channels. [1] This change in conformation is a response to changes in transmembrane voltage.
Ionic bonding is a type of chemical bonding that involves the electrostatic attraction between oppositely charged ions, or between two atoms with sharply different electronegativities, [1] and is the primary interaction occurring in ionic compounds. It is one of the main types of bonding, along with covalent bonding and metallic bonding.
For example, the ion channels involved in the action potential are voltage-sensitive channels; they open and close in response to the voltage across the membrane. Ligand-gated channels form another important class; these ion channels open and close in response to the binding of a ligand molecule, such as a neurotransmitter. Other ion channels ...