Electric action

Another important property of the outer membranes of nerve and muscle cells is their susceptibility to excitation under the effect of electric action. Excitation can be brought about, for example, by an external electric current pulse. Pulses can be applied to the membrane with the aid of two microelectrodes, one residing in the extracellular fluid and the other introduced through the membrane into the cytoplasm. 

Potassium is the second most abundant cation in the body and is found primarily in the intracellular fluid. Potassium has many important physiologic functions, including regulation of cell membrane electrical action potential (especially in the myocardium), muscular function, cellular metabolism, and glycogen and protein synthesis. Potassium in PN can be provided as chloride, acetate, and phosphate salts. One millimole of potassium phosphate provides 1.47 mEq of elemental potassium. Generally, the concentration of potassium in peripheral PN (PPN) admixtures should not exceed 80 mEq/L (80 mmol/L). While it is safer to also stick to the 80 mEq/L (80 mmol/L) limit for administration through a central vein, the maximum recommended potassium concentration for infusion via a central vein is 150 mEq/L (150 mmol/L).14 Patients with abnormal potassium losses (e.g., loop or thiazide diuretic therapy) may have higher requirements, and patients with renal failure may require potassium restriction. 

White lead processes which have been employed on an industrial scale are as follows In the Gardner1 process, worked at Millwall, lead sheet anodes are packed between graphite cathodes. The lead and graphite are connected by strips of tin so that when the acetic acid vapours reach the metal, electrical action takes place and the conversion into white lead is greatly accelerated. The process is similar to the ordinary chemical one, but the time required for the formation of a batch of white lead is reduced from fourteen weeks to about five weeks. 

Electrical action of the heart, normal, says the heart specialist. No danger of a heart attack for you. ... 

If H. Sainte-Claire Deville s way of veiwing this is correct, these syntheses should not be regarded as indirect reactions, rendered possible by a certain electrical action, but as reactions which are produced directly at high temperatures the apparatus with cold and hot tubes should suffice to produce them without making any use of electricity. 

Neurons communicate with each other (as well as with other non-neural cells) either via electrical (action potential) or... 

Potassium regulates many biochemical processes in the body, and is a key ion for electrical action potentials across cellular membranes. 

In the retina, there are two kinds of light-sensing cells, rods and cones, that convert incoming photons into neuronal action potentials. When cones are activated by photons of light, pigment molecules change shape and produce electrical action potentials that pass information throughout the brain. 

The release of neurotransmitters and their recognition by receptors on the postsynaptic neuron control the electrical action potentials that transmit the information. The intensity of electrical activity is modulated by neurotransmitters produced in the neuronal cell bodies and transported along axons to their terminals, where they are stored until secreted into the synapse. As the result of electrical action potentials traveling down axons, neurotransmitters are released into the synapses. After the neurotransmitter enters the synapse, it modulates the electrical activity of the postsynaptic neuron. 

In 1921, an Austrian scientist, Otto Loewi, discovered ACh, the first neurotransmitter. At the time, it was difficult for neuroscientists to believe that molecules could affect neuronal activity. The principal focus was on electrical action potentials. 

After release from storage sites in presynaptic monoamine transporter vesides, DA is bound by postsynaptic DA receptors, and unbound DA is broken down by enzymes, or taken back into presynaptic neurons, called reuptake into presynaptic neurons by spedfic presynaptic protein transporters. The uptake of neurotransmitters by presynaptic neurons is a major mechanism for stopping neurotransmission. The recyded neurotransmitter is repackaged in vesicles in presynaptic neurons, and then rdeased again in response to stimulation by presynaptic electrical action potentials. Tracers have been developed to assess the vesicular membranes, as well as the specific reuptake protein transporters. The selectivity with which monoaminergic neurons store DA, 5-HT, NER, or histamine in presynaptic vesides depends on the spedficity of the membrane transporters. 

In 1936, Loewi received the Nobel Prize with Henry Dale. They discovered that acetylcholine has two types of action. The drug, atropine, produces the muscarinic effert of acetylcholine by binding to muscarinic acetyldioline receptors. Acetylcholine also has nicotinic actions, stimulating the autonomic nervous system and voluntary muscle fibers. Nicotine stimulates the noradrenergic system. It acts by opening ion chaimels across the membranes of post-synaptic neurons, which generates electrical action potentials. 

All the facts show us that the power commonly called chemical affinity, can be communicated to a distance through the metals and certain forms of carbon that the electric current is only another form of the forces of chemical affinity that its power is in proportion to the chemical affinities producing it that when it is deficient in force it may be helped by calling in chemical aid, the want in the former being made up by an equivalent of the latter that, in other words, the forces termed chemical affinity and electricity are one and the same. . . both chemical and electrical actions are merely two exhibitions of one and the same power. ... 

Our study has been essentially theoretical. Chemical processes have been simplified the reaction rate is written as the product of terms assumed independent and taking into account the effects of pH and of the concentrations of substrate, cofactor, activator or inhibitor. When these species are ionic, they are called the mediators of the electrical action. For this study of complex dynamics, we have considered a system modelling the reaction catalyzed by uricase ... 

Simon W (1965) The real-time sotting of neuro-electric action potentials in multiple unit studies. Electroenceph CUn Neurophysiol. 18 192-195. 

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