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Topic: Cell potential


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  Standard Electrode Potentials
This potential is a measure of the energy per unit charge which is available from the oxidation/reduction reactions to drive the reaction.
The cell potential (often called the electromotive force or emf) has a contribution from the anode which is a measure of its ability to lose electrons - it will be called its "oxidation potential".
The standard electrode potentials are customarily determined at solute concentrations of 1 Molar, gas pressures of 1 atmosphere, and a standard temperature which is usually 25°C. The standard cell potential is denoted by a degree sign as a superscript.
hyperphysics.phy-astr.gsu.edu /hbase/chemical/electrode.html   (1055 words)

  
 What are the potential uses of human stem cells and the obstacles that must be overcome before these potential uses ...
Perhaps the most important potential application of human stem cells is the generation of cells and tissues that could be used for cell-based therapies.
Other recent studies in cell culture systems indicate that it may be possible to direct the differentiation of embryonic stem cells or adult bone marrow cells into heart muscle cells (Figure 4).
New studies indicate that it may be possible to direct the differentiation of human embryonic stem cells in cell culture to form insulin-producing cells that eventually could be used in transplantation therapy for diabetics.
stemcells.nih.gov /info/basics/basics6.asp   (956 words)

  
 CBHD: Cloning and Stem Cell Research - Dónal P. O'Mathúna
Obtaining cells from an embryo which has been cloned by inserting a patient's own DNA into an egg cell devoid of genetic material circumvents the risk of tissue rejection which would likely be posed if stem cells were derived from non-cloned embryos who do not share the patient's genetic material.
If the stem cells obtained from these cloned embryos could be coaxed into becoming skin cells, they would be genetically identical to the patient and would pose no risk of rejection.
Yet precisely the same potential is lost when a human embryo, cloned or not, is torn apart to supply stem cells for the benefit of another.
www.cbhd.org /resources/stemcells/omathuna_fall-2000.htm   (1370 words)

  
 Membrane potential Summary
Action potentials are transient spikes in membrane potential characterized by initiating membrane potential changes that start the transmembrane flow of charged solutes through voltage-gated ion channels which in turn results in new membrane potential changes that ultimately return the membrane potential to the value it had at the start of the spike.
The typical membrane potential of a cell arises from the separation of potassium ions from intracellular immobile anions across the membrane of the cell.
In the case of the standard membrane potential across a cell's plasma membrane, potassium (and sodium) gradients are established by the NaKATPase (sodium potassium exchanger).
www.bookrags.com /Membrane_potential   (3773 words)

  
 Action potential - Biocrawler   (Site not responding. Last check: 2007-09-09)
As the cell membrane is hydrophobic, charged molecules or ions are not able to easily diffuse through it, this property permits a potential difference to exist across the membrane.
While the cell is at resting cell potential the electric forces between the sodium and potassium of the neuron is counterbalanced by the "diffusive forces," creating a state of equilibrium.
Where membrane has undergone an action potential a refractory period follows, during which a second action potential is inhibited due to the reversible inactivation of ion channels.
www.biocrawler.com /encyclopedia/Action_potential   (0 words)

  
 CellEMF   (Site not responding. Last check: 2007-09-09)
The standard cell potential is given by the standard reduction potential of the cathode, minus the standard reduction potential of the anode
Whenever we assign a potential to a half-reaction using the equation for the standard cell potential, it is always done in reference to a reduction reaction
Thus, in reference to the SHE, the oxidation of Zn(s) is associated with a half-cell potential of +0.76V (this is the spontaneous direction for the reaction; the reduction of Zn and the oxidation of H
wine1.sb.fsu.edu /chm1046/notes/Electro/CellEMF/CellEMF.htm   (0 words)

  
 Action potential at AllExperts
Action potentials can be created by many types of cells, but are used most extensively by the nervous system for communication between neurons and to transmit information from neurons to other body tissues such as muscles and glands.
Action potentials are largely dictated by the interplay between sodium and potassium ions (although there are minor contributions from other ions such as calcium and chloride), and are often modeled using hypothetical cells containing only two transmembrane ion channels (a voltage-gated sodium channel and a non-voltage-gated potassium channel).
Cell membranes that contain ion channels can be modeled as RC circuits to better understand the propagation of action potentials in biological membranes.
en.allexperts.com /e/a/ac/action_potential.htm   (3542 words)

  
 The Endocochlear Potential
In the middle of stria vascularis are the capillaries and intermediate cells.
Thus the potential of the marginal cells is highly positive, but that potential is not generated across either the basolateral or apical membranes of the marginal cell.
Basal cells, intermediate cells and fibrocytes of the spiral ligament are joined by gap junctions, which are believed to be required to facilitate K movements towards the endolymph.
oto.wustl.edu /cochlea/ep.htm   (1301 words)

  
 Membrane potential - Wikipedia, the free encyclopedia
Action potentials are transient spikes in membrane potential characterized by initiating membrane potential changes that start the transmembrane flow of charged solutes through voltage-gated ion channels which in turn results in new membrane potential changes that ultimately return the membrane potential to the value it had at the start of the spike.
The typical membrane potential of a cell arises from the separation of potassium ions from intracellular immobile anions across the membrane of the cell.
In the case of the standard membrane potential across a cell's plasma membrane, potassium (and sodium) gradients are established by the NaKATPase (sodium potassium exchanger).
en.wikipedia.org /wiki/Transmembrane_potential   (0 words)

  
 Princeton Applied Research - Fuel Cell   (Site not responding. Last check: 2007-09-09)
The fuel cell is an energy conversion device that theoretically has the capability of producing electrical energy for as long as fuel and oxidant are supplied to the electrodes.
In a typical fuel cell, gaseous fuels are fed continuously to the anode (negative electrode) and anoxidant (i.e., oxygen from air) is fed continuously to the cathode (positive electrode); the electrochemical reactions take place at the electrodes to produce an electric current.
The fuel cell, on the other hand, is an energy conversion device that theoretically has the capability of producing electrical energy for as long as fuel and oxidant are supplied to the electrodes.
www.princetonappliedresearch.com /products/markets/fuel_cell.cfm   (1817 words)

  
 Greater potential of adult stem cells revealed - 17 May 2003 - New Scientist
Such cells could be taken from an individual and used to generate any kind of tissue needed by that person, such as muscle tissue for repairing damaged hearts.
That means stem cells from one person could be used to treat many others, instead of each individual having to be treated with their own cells.
Put the properties of the two kinds of cell together and all of a sudden you have a non-controversial, highly versatile source of adult stem cells that can, in theory, be transplanted to anyone, because the cells do not trigger an immune reaction.
www.newscientist.com /article.ns?id=dn3723   (0 words)

  
 Scientific American: The Stem Cell Challenge   (Site not responding. Last check: 2007-09-09)
For scientists to be able to share results and gauge the success of techniques for controlling stem cell behavior, we must first know that the cells we are studying actually possess the ability to serve as the source, or "stem," of a variety of cell types while themselves remaining in a generic state of potential.
ES cells and their derivatives carry the same likelihood of immune rejection as a transplanted organ because, like all cells, they carry the surface proteins, or antigens, by which the immune system recognizes invaders.
As is true of embryonic cells, so little is understood about the factors that may control the adult stem cells' fate that we do not yet know whether extensive time spent in culture could harm their ability to restore tissues in patients.
www.sciam.com /print_version.cfm?articleID=000DFA43-04B1-10AA-84B183414B7F0000   (3323 words)

  
 Resting potential - Wikipedia, the free encyclopedia
The resting potential of a cell is the membrane potential that would be maintained if there were no action potentials, synaptic potentials, or other active changes in the membrane potential.
The resting potential is mostly determined by the concentrations of the ions in the fluids on both sides of the cell membrane and the ion transport proteins that are in the cell membrane.
The Nernst equation is used to estimate the equilibrium potential for an ion.
en.wikipedia.org /wiki/Cell_potential   (0 words)

  
 Obtaining Effective Half-Cell Potential Measurements in Reinforced Concrete Structures - NRC-IRC
The half-cell potential measurement is an electrochemical technique commonly used by engineers to assess the severity of corrosion in reinforced concrete structures.
Half-cell potential measurements made on reinforced concrete with organic coatings and sealers may prove to be inaccurate or impossible owing to their high resistance.
For example, the half-cell potential shift may be associated with corrosion activity that is high or low, or a particular situation may not relate to the reinforcement corrosion probability.
irc.nrc-cnrc.gc.ca /pubs/ctus/18_e.html   (1976 words)

  
 Reports - Meeting Summary - Stem Cell Biology: Potential and Promise
A stem cell is a cell that is self-renewing, i.e., capable of repeated cell divisions, and pluripotent, i.e., capable of giving rise to several different types of cells.
Another issue is that, for clinical purposes, culture of stem cells has to be undertaken under sterile conditions, as well as conditions that preclude cross-contamination of the stem cells from one donor with those of another.
Animal infarct models have suggested that there is potential for the repair of damage to heart muscle or for the treatment of certain types of heart disease with stem cells.
www.niams.nih.gov /ne/reports/sci_wrk/2000/stemcellmeetsummary.htm   (1111 words)

  
 Cell membrane potential- first page   (Site not responding. Last check: 2007-09-09)
Cell membrane potential in excitable cells - summary
They are designed to make easier the understanding of the basic principles of generation and spreading of electric potential in excitable cells.
Here you can simulate how the input through the presynaptic cell generates postsynaptic potential and when it is high enough, the postsynaptic cell starts to fire spikes.
www.emile-21.com /VRML/membPot0.html   (0 words)

  
 Stem-cell potential tantalizes scientists
A stem cell research institute proposed for Camden would tackle some of the biggest questions in science and use the answers to develop innovative new treatments for ailments ranging from depression to cancer.
The root of much of the anticipated research is the stem cell, which can with proper care become any part of a body, from a bone cell to a red blood cell.
As it is, maintaining healthy stem cells while preventing them from transforming into other kinds of cells is a tricky business, he said.
www.engl.stem-cell.ru /news/phpnews/cell_news.php?nom_news=474   (0 words)

  
 Electrochemical_Cell_Potentials
A cell's standard state potential is the potential of the cell under standard state conditions, which is approximated with concentrations of 1 mole per liter (1 M) and pressures of 1 atmosphere at 25
To determine the cell potential when the conditions are other than standard state (concentrations not 1 molar and/or pressures not 1 atmosphere):
Example: Predict the cell potential for the following reaction when the pressure of the oxygen gas is 2.50 atm, the hydrogen ion concentration is 0.10 M, and the bromide ion concentration is 0.25 M. (g) + 4 H
www.chem.purdue.edu /gchelp/howtosolveit/Electrochem/Electrochemical_Cell_Potentials.htm   (410 words)

  
 Fuel Cell Market Trends Report
Fuel cells have the potential to become the dominant technology for automotive engines, power stations, and power packs for portable electronics.
Solid oxide cells are still struggling to make the jump from the research lab to the market and to find practical applications.
Phosphoric acid fuel cell unit numbers remained practically unchanged in 2005, and thus the cumulative market share went down, but this trend is expected to change within two years when UTC releases a new enhanced PAFC with a lifespan of 80,000 operating hours, the highest in the market.
www.fuelcelltrends.com   (0 words)

  
 AMA (CSAPH) Report 15 of the Council on Scientific Affairs (I-99) Full Text
 Embryonic stem cells are derived from embryonic gondal tissue (germline cells).
He argues that the derivation of stem cells from the blastocyst stage, with removal of the outer cellular layer of the blastocyst, means the placenta cannot form, which is a requisite for implantation in the uterus and the beginning of fetal development.
It is interesting that the prospect of stem cell research impacting tremendously on the potential for cures for adult-onset disorders represents a counterbalance to the previous context of embryo research, mainly the abortion issue.
www.ama-assn.org /ama/pub/category/13594.html   (6002 words)

  
 Potential of cell   (Site not responding. Last check: 2007-09-09)
The existence of an open circuit potential indicates that although each phase within the cell is in a state of equilibrium with adjacent phases, the cell as a whole is not at a state of equilibrium.
For a spontaneous reaction (a galvanic cell or energy producer) the cell potential is positive.
The state of equilibrium is reached by the transfer of charged particles across the interface until the difference in chemical potential is balanced by a potential difference between the two phases.
www.tannerm.com /cellpot.htm   (372 words)

  
 NIH Guide: STEM CELL POTENTIAL OF THE MAMMALIAN OLFACTORY EPITHELIUM
The NIDCD encourages applications from investigators who are conducting research outside the field of olfaction and possess expertise in stem cell biological research, and who are using methodological approaches that have not been typically applied to but which would greatly promote scientific progress within the field of olfaction.
Such replacement and proliferation are possible due to the presence of precursor, multipotent stem cells in the olfactory epithelium.
This RFA is soliciting applications focused on the genetic, molecular and cellular mechanisms that regulate the lineage, differentiation and proliferation of the multipotent stem cells in the olfactory epithelium.
grants.nih.gov /grants/guide/rfa-files/RFA-DC-03-002.html   (0 words)

  
 UF SCIENTISTS EXPLORE ADULT STEM CELL POTENTIAL   (Site not responding. Last check: 2007-09-09)
But while the possibilities for adult stem cells were once thought to be sharply limited, recent discoveries suggest that like their younger brethren, they also may one day be manipulated to generate transplant tissues or awaken the body's dormant powers of self-repair.
Many scientists have prized embryonic stem cells because their early stage of development gives them the ability to generate all of the body's tissue types - a gold mine for efforts to develop treatments for a wide range of diseases or even to grow whole organs to replace damaged or dying body parts.
With the finding that mature cells can return to the primitive stem cell state, Steindler and other researchers, including Tanya Ignatova in his lab, are investigating whether some tumors may originate from a newly created stem cell whose DNA has been damaged.
www.napa.ufl.edu /2001news/stemcells.htm   (822 words)

  
 Fuel Cell Works Supplemental News Page
A fuel cell is similar to a battery in that it produces electricity in an electrochemical reaction.
Unlike a battery, a fuel cell uses external reactants, typically oxygen and hydrogen, as fuel for the reaction.
South Africa is an ideal site for the first tests of fuel cell systems as the country is one of the world's leading producers of both platinum and gold, two metals that are essential to the hydrogen economy.
www.fuelcellsworks.com /Supppage4365.html   (471 words)

  
 Standard Electrode Potentials
After studying this section, you will (a) know the meaning of the term "standard electrode potential", (b) understand the relationship between the electromotive force of a cell and the standard electrode potentials of its half cells, (c) be able to use a table of standard electrode potentials in order to calculate the e.m.f.
The cell potential (emf) of this cell under standard conditions is 1.10 V (volt).
The emf of the cell (1.10 V) is the potential difference between the electrodes of the cell, which is the difference between the abilities of the half-cells to attract electrons.
www.physchem.co.za /Redox/SEP.htm   (650 words)

  
 Standard cell voltages and half cell voltages
Rather than tabulate standard cell potentials for all possible electrochemical cells (a huge number), potentials for half cells (anode or cathode) are tabulated.
That is, the net cell potential is the difference between the cathode and anode half cell potentials, when each is written as a reduction reaction.
Also, note that the cell potentials are not multiplied by the number of moles like the free energies are.
www.nyu.edu /classes/tuckerman/honors.chem/lectures/lecture_26/node2.html   (390 words)

  
 Voltaic Cells   (Site not responding. Last check: 2007-09-09)
Standard Reduction Potentials are the voltage generated when a half cell of a certain substance is connected to a reference half cell compartment.
Determining the cell potential of this Copper-Zinc voltaic cell would simply be the sum of the reduction potential and the oxidation potential.
A Cobalt half cell with Co at.01 M and a Cobalt electrode is connected to a Gold half cell with Au at.1 M and a Gold electrode.
members.aol.com /logan20/voltaic.html   (2559 words)

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