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Topic: Resting membrane potential


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In the News (Mon 24 Jun 19)

  
  Membrane potentials
Membrane potentials are determined primarily by three factors: 1) the concentration of ions on the inside and outside of the cell; 2) the permeability of the cell membrane to those ions (i.e., ion conductance) through specific ion channels; and 3) by the activity of electrogenic pumps (e.g., Na
At the peak of the action potential in a cardiac cell (e.g., ventricular myocyte), the membrane potential is approximately +20 mV.
However, to fully understand how multiple ions affect the membrane potential, and ultimately how the membrane potential changes during action potentials, it is necessary to learn how changes in membrane ion permeability, that is, changes in ion conductance, affect the membrane potential.
www.cvphysiology.com /Arrhythmias/A007.htm   (827 words)

  
 Membrane potential - Wikipedia, the free encyclopedia
Membrane potential (or transmembrane potential or transmembrane potential difference or transmembrane potential gradient), is the electrical potential difference (voltage) across a cell's plasma membrane.
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.
en.wikipedia.org /wiki/Membrane_potential   (3001 words)

  
 Neuroscience: A Journey Through the Brain - The Action Potential
However, the membrane is permeable at rest to several ions, and their relative permeability must be taken into consideration when calculating the membrane potential.
Threshold: Threshold is the membrane potential at which enough voltage-gated sodium channels are open so that the relative permeability of the membrane is higher for sodium ions than it is for potassium ions.
The propagation of the action potential occurs because the influx of positive charge during the rising phase depolarizes the next segment of the membrane.
www.ualberta.ca /~neuro/OnlineIntro/NeuronAP.htm   (748 words)

  
 Changes in the Membrane Potential
We know that the resting membrane is mainly permeable to K+, and thus the resting membrane potential should be close to the K+ equilibrium potential.
However, the resting membrane potential is not exactly at the equilibrium potential for K+, but a bit higher at -70 mV.
This is because the resting membrane is slightly permeable to Na+.
courses.washington.edu /physeng/membpot/changepotential.htm   (510 words)

  
 IONIC BASIS OF THE RESTING MEMBRANE POTENTIAL
The electrical potential difference between the inside and the outside of the cell (the membrane potential) depends upon the ionic concentration gradients across the cell and the relative permeability of the membrane to the ions present in the cell.
At rest the active fluxes driven by the pump and the passive fluxes due to diffusion along conc gradients are balanced – the cell is in a steady state.
The membrane potential dips down lower than it would at the resting potential because of the two populations of K channels open (voltage dependent and also passive channels).
www.bioweb.uncc.edu /humanphys/resting.htm   (2437 words)

  
 A Brief Introduction to the Brain:Membrane Potential
Electrical signals (receptor potential, synaptic potential and action potential) are all caused by transient changes in the current flow into and out of the neuron, that drives the electrical potential across the plasma membrane away of its resting condition.
Since, by convention, the potential outside the cell is arbitrarily defined as zero, and given the relative excess of negative charges inside the membrane; the potential difference across the membrane is expressed as a negative value:
Transient current flow and therefore rapid changes in potential are made possible by ion channel, a class of integral proteins that traverse the cell membrane.
ifcsun1.ifisiol.unam.mx /Brain/mempot.htm   (792 words)

  
 Nerve Impulses   (Site not responding. Last check: 2007-10-26)
The membrane potential is always negative inside the cell, and varies in size from –20 to –200 mV (milivolt) in different cells and species (in humans it is –70mV).
At rest, the inside of the neuron is slightly negative due to a higher concentration of positively charged sodium ions outside the neuron.
This means that, although the action potential affects all other ion channels nearby, the upstream ion channels cannot open again since they are in their refractory period, so only the downstream channels open, causing the action potential to move one-way along the axon.
www.biologymad.com /NervousSystem/nerveimpulses.htm   (2352 words)

  
 Ionic Basis of Resting Potential
The membrane itself is the barrier to free ion flow between the inside and outside of the cell.
Because of this complex movement of ions, it’s relatively difficult to predict the membrane potential of the cell from the equilibrium potential of the various ions to which the cell is permeable.
At the resting potential we calculated earlier, none of the three major ions were at their equilibrium potentials.
www.lclark.edu /~reiness/neurobiology/Lectures/lecture3.htm   (3105 words)

  
 Neuron Resting Potential
There is a potential difference across the membranes of most cells, with the inside of the cell negative relative to the outside of the cell.
Distribution of ions across the membrane and membrane permeability are responsible for the potential difference across the membrane.
Resting membrane potential - a polarization or electrical difference between the inside and outside of inactive cells caused by concentration differences of certain ions and selective membrane permeability.
www.mtsu.edu /~jshardo/bly2010/nervous/restpot_nonav.html   (296 words)

  
 [No title]
An electrical gradient between the extracellular fluid is known as the resting membrane potential difference, which when broken apart stands for: The resting refers to the fact that this electrical gradient is seen in all living cells, even those that appear to be without electrical activity.
The potential part comes from the fact that an electrical gradient is created by active transport of ions across the cell membrane The difference reminds you that it represents a difference of electrical charge between the inside and the outside of the cell.
In the top-third of the rising phase, the membrane potential reversed polarity; that is the inside of the cell is now positive as compared to the outside.
www.library.csi.cuny.edu /~yelsherif/electrophysiology.doc   (2240 words)

  
 Biology 304 Laboratory Two: Resting Potential
This potential difference arises because there is an uneven distribution of ions inside and outside the cell and because the cell membrane shows differential permeability to the different ionic species that are present.
The membrane potential is measured with a glass microelectrode inside the cell relative to a reference electrode in electrical contact with the extracellular solution.
A silver/silver chloride reference electrode (remember that potential difference is always measured relative to something) in the bath (or in a small beaker of 3 M KCl in electrical contact with the bath through an agar/electrolyte bridge) connects to the amplifier at the input marked "REF" and this completes the recording circuit.
www.williams.edu /BIMO/liz/LAB2.html   (2567 words)

  
 Biology
Though the intracellular concentration is high for potassium and low for both chloride and sodium, the resting membrane potential opposes potassium and chloride ions from diffusing down their concentration gradients.
Note that the value of the resting membrane potential is closer to the value of the potassium potential.
The action potential can be described as a resting potential activated by a sharp rising phase (depolarization) followed by a rapid falling phase extending below the original resting potential (hyperpolarization).
www.swarthmore.edu /NatSci/echeeve1/Ref/HH/BioWriteUp.htm   (1152 words)

  
 Human Physiology - Neurons & the Nervous System
An action potential is a very rapid change in membrane potential that occurs when a nerve cell membrane is stimulated.
All these positively-charged sodiums rushing in causes the membrane potential to become positive (the inside of the membrane is now positive relative to the outside).
As a result, for a split second, areas of membrane adjacent to each other have opposite charges (the depolarized membrane is negative on the outside and positive on the inside, while the adjacent areas are still positive on the outside and negative on the inside).
people.eku.edu /ritchisong/301notes2.htm   (2090 words)

  
 A Ba2+-Sensitive K+ Current Contributes to the Resting Membrane Potential of Neurons in Rat Suprachiasmatic Nucleus -- ...
this resting conductance and to the genesis of the resting membrane
Application of 500 µM Ba depolarized the membrane potential of this cell by 4 mV and simultaneously increased firing frequency of this cell from 0.9 to 2.0 Hz.
Membrane properties and morphology of vasopressin neurons in slices of rat suprachiasmatic nucleus.
jn.physiology.org /cgi/content/full/88/2/869   (5111 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.
For determination of membrane potentials, the two most important types of membrane ion transport proteins are ion channels and ion pumps.
en.wikipedia.org /wiki/Resting_potential   (606 words)

  
 Ionic basis of the resting membrane potential
This potential difference results from a separation of charge across the cell membrane: there is an excess of positive charges on the extracellular face of the membrane and an excess of negative charges on the inside of the cell membrane.
It should be noted that the small excess of anions at the inner surface of the cell membrane and cations at the outer surface that create the resting potential is negligible relative to the total number of ions in the bulk intracellular and extracellular solutions.
The cell membrane is composed of a mosaic of lipids and proteins.
www.williams.edu /BIMO/liz/LEC2.html   (1753 words)

  
 Neurophysiology
Resting membrane potential (Vr) - The resting membrane potential is a measurement of the voltage across a cell membrane.
Note that the (-) indicates that the inside of the cell (cytoplasmic side of the membrane) is more negative than the extracellular side of the membrane.
The resting membrane potential varies from -40 mV to -90 mV depending on the neuron type.
www.etsu.edu /cpah/hsci/forsman/neurophys.htm   (699 words)

  
 Resting membrane potential regulates Na+-Ca2+ exchange-mediated Ca2+ overload during hypoxia-reoxygenation in rat ...
This appears to be due mainly to an effect of diastolic membrane potential on the Na -Ca exchanger, since at depolarized potentials this exchanger mechanism operates in the reverse mode, causing a significant Ca influx.
In most cases, the characteristic 'two stable membrane potential' behaviour of a cell in which the resting potential is generated by a strong inward rectifier was observed.
We conclude that the magnitude of reoxygenation-induced Ca overload is dependent on membrane potential, and that this effect is primarily mediated by Ca influx due to the Na -Ca exchanger.
jp.physoc.org /cgi/content/full/550/3/889   (6204 words)

  
 The Neural Membrane and Resting Potential
A neuron, or section of a neural membrane, that is currently not involved in sending or recieving a message, has a membrane potential of about -70 mV.
As the membrane potential is decreased either by gaining more positive ions, or loosing negative ions it is said to be depolarizing (even when the membrane potential reaches positive numbers it is still called a depolarization).
When the membrane potential is increased due to a net gain of negative ions (or coresponding loss of positive ions) the membrane is said to be hyperpolarized.
www.fortunecity.com /greenfield/buzzard/387/neuralmemrmp.htm   (1125 words)

  
 Generation of resting membrane potential -- Wright 28 (4): 139 -- Advances in Physiology Education
is the membrane permeability (in cm/s) for the indicated
membrane permeability to ions is defined by the activity of
decrease in the stability of the resting membrane potential.
advan.physiology.org /cgi/content/full/28/4/139   (2563 words)

  
 Neuroscience for Kids - Action Potential
When a neuron is not sending a signal, it is "at rest." When a neuron is at rest, the inside of the neuron is negative relative to the outside.
The resting membrane potential of a neuron is about -70 mV (mV=millivolt) - this means that the inside of the neuron is 70 mV less than the outside.
Action potentials are caused by an exchange of ions across the neuron membrane.
faculty.washington.edu /chudler/ap.html   (767 words)

  
 Potentials
The peak amplitude of the action potential is determined to some extent by the sodium concentration gradient between the outside and inside of the cell.
An action potential is the rapid reversal of membrane potential seen after an excitable cell has been depolarized to its threshold potential.
In neurons action potentials have a short duration of from 1 - 5 ms and, in any single neuron, under the same conditions, the duration and amplitude of one action potential is identical to all other action potentials generated in that neuron.
www.cofc.edu /~munrod/Potentials.html   (2226 words)

  
 FBR ScienceWorks for ME - Long QT-Resting Membrane Potential
Long QT Syndrome and the Resting Membrane Potential: From Microscopic to Macroscopic is a curricular unit devised by FBR's Dr. Walt Allan, a pediatric neurologist.
In Long QT syndrome, this disturbance is caused by an inherited mutation in a gene that regulates one of the ion channels in heart muscle cells.
An objective of this lab is to demonstrate that the inherited defect in ion channels alters the repolarization phase of the action potential, leading to prolongation of the QT interval and to sudden death in Long QT syndrome.
www.fbr.org /swksweb/lqtrmp.html   (328 words)

  
 FBR ScienceWorks for ME - Long QT Syndrome Outline
That is, if you place an electrode in the cytosol on the inside of a cell and connect it to an electrode in the extracellular fluid, you will find a difference in electrical energy between these two spaces that will produce a flow of electrons in the connecting wire.
The resting membrane potential is present in all cells, regardless of type, and can constitute a definition of life for cells - if the cell lacks a membrane potential it is dead!
A lot of the chemical machinery of cells is involved with the maintenance of this membrane potential.
www.fbr.org /swksweb/lqtintro.html   (284 words)

  
 Action Potential   (Site not responding. Last check: 2007-10-26)
The action potential is an electrical phenomenon that occurs in nerve cells (or neurons).
The neuron starts at resting membrane potential which is around -70 mv (inside of the neuron is negative compared to outside).
So, the action potential is called a brief reversal of membrane potential because it starts at about -70 mv, goes up to around +30 mv, and back to -70 mv.
www.zerobio.com /central/actionpotential.htm   (258 words)

  
 Mapping of capillary flow, cellular redox state, and resting membrane potential in hypoperfused rat myocardium -- ...
potential, thereby causing a reduction in the transmembrane potential.
Membrane potential can be determined in individual cells from the Nernstian distribution of cationic dyes.
Measurement of membrane potential of endothelial cells in single perfused microvessels.
ajpheart.physiology.org /cgi/content/full/277/5/H2050   (7528 words)

  
 Uncovering misconceptions about the resting membrane potential -- Silverthorn 26 (2): 69 -- Advances in Physiology ...
Resting membrane potential is one of the most difficult physiological
to the resting membrane potential of an adipose cell?
membrane potential difference increased, but they had no further
advan.physiology.org /cgi/content/full/26/2/69   (789 words)

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