Potassium ions biology

Potassium hexachloromolybdate, 3, 1230 Potassium hexacyanoferrate discovery, 1, 3 Potassium ions biology, 6, 559 selective binding biology, 6, 551... 

Sodium hexakis(formato)molybdate, 3, 1235 Sodium hypochlorite alkene epoxidation manganese catalysts, 6,378 Sodium ions biology, 6, 559 selective binding biology, 6, 551 Sodium molybdate, 3, 1230 Sodium peroxoborate, 3,101 Sodium/potassium ATPase, 6, 555 vanadate inhibition, 3, 567 Sodium pump, 6, 555 mechanism, 6, 556 Sodium pyroantimonate, 3, 265 Sodium salts... 

In living systems, chlorine is present as chloride, Cl . In part, chloride is there to balance ont the charges contributed by cations such as sodium and potassium ions. There are mechanisms to get chloride across biological membranes as required to maintain charge neutrality. When such a mechanism goes wrong, it is a problem. 

It is interesting to note that the main cation present in ICF is the potassium ion, whereas the principal cation in ECF is the sodium ion. The role of potassium and sodium ions in the biological system is described in the entry on Potassium and Sodium (In Biological Systems). 

We may now assemble the foregoing information into a molecular description of a few biological processes in which the interaction between water and metal ions plays an important role. First some problems related to signal transfer in nerve cells are discussed. This is followed by some comments on the mechanism operating at nerve synapses in which, in addition to the sodium and potassium ions, a specific transmitter substance and calcium ions take part. 

The examples given here of the use of MM in synthesis are taken from the review by Lipkowitz and Peterson [28]. In attempts to simulate the metal-binding ability of biological acyclic polyethers, the tricyclic 1 (Fig. 3.12) and a tetracyclic analogue were synthesized, using as a guide the indication from MM that these molecules resemble the cyclic polyether 18-crown-6, which binds the potassium ion the acyclic compounds were found to be indeed comparable to the crown ether in metal-binding ability. 

Humans and other vertebrates must have sodium and potassium in their diets because many biological functions are controlled by sodium and potassium ions. Potassium ions are the most common positive ions within cells. Sodium ions are the most common positive ions in the fluid that surrounds cells. When a nerve cell is stimulated, sodium ions flow into the cell and potassium ions flow out. This flow of ions across the cell membrane carries the nerve impulse along the cell. After the impulse passes, a compound attached to the cell membrane uses energy to move the ions back across the membrane so that they are in position for the next impulse. 

Sodium and potassium are the most abundant alkali metals. Many biological functions are controlled by sodium and potassium ions. 

The polyether nonactin (174) is an antibiotic tetralide produced by the Streptomyces family of microorganisms. From a biological point of view, nonactin and the other compounds in this family of tetrameric lactones have the ablility to strongly complex potassium ion and to facilitate the transport of potassium across membranes by providing a lipophilic shell. Ion transport has been shown to have a strong influence on important biological functions such as oxidative phosphorylation and mitochondrial respiration. 

Most of the recent interests in this group of metal ions — as far as their properties in solution are concerned — arose in biology, more specifically in neurobiology. Sodium and potassium ions are the major ionic constituents of all inter- and extracellular liquids, and play an outstanding role in electric communication across membranes. The excitation of the nervous membrane, for instance, is closely linked with a rapid exchange of sodium and potassium ions, which in the resting state are separated by means of an active transport mechanism. 

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