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Topic: Action potential


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In the News (Thu 23 May 19)

  
  Welcome to the Action Potential, Inc. Website
The mission of Action Potential, Inc. is to advance research and to provide timely, accurate information to doctors so they can administer state of the art patient care.
Action Potential, Inc. was founded in 1987 by Ronald L. Rupert D.C..
Action Potential, Inc. is recognized as the profession's research literature experts and is the only company providing these services for prominent professional organizations like the American Chiropractic Association (ACA) and the Foundation for Chiropractic Education and Research (FCER).
www.action-potential.com   (461 words)

  
 Neuroscience for Kids - Action Potential
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.
Also, when the threshold level is reached, an action potential of a fixed sized will always fire...for any given neuron, the size of the action potential is always the same.
Action potentials are caused by an exchange of ions across the neuron membrane.
faculty.washington.edu /chudler/ap.html   (767 words)

  
  action potential - multiple sclerosis encyclopaedia   (Site not responding. Last check: )
The action potential is an explosive release of charge between a nerve cell (neuron) and its surroundings.
The resting potential is maintained by a "semi-permeable membrane" or "phospholipid bilayer" around the nerve cell which allows some ions to pass through it but not others.
When the action potential reaches the end of an axon, it causes special chemical messages called neurotransmitters to be released across the space between the neurons (the synapse).
www.mult-sclerosis.org /actionpotential.html   (847 words)

  
  Action potential Summary
An action potential represents a change in electrical potential from the resting potential of the neuronal cell membrane, and is a series of electrical and underlying chemical changes that travel down the length of a neural cell (neuron).
The standing potential is maintained because, although there are both electrical and concentration gradients (a range of high to low concentration) that induce the excess sodium ions to attempt to try to enter the cell, the channels for passage are closed and the membrane remains almost impermeable to sodium ion passage in the rest state.
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).
www.bookrags.com /Action_potential   (5382 words)

  
  Action potential
In his discovery of "animal electricity," Luigi Galvani elicited an action potential through contact of his scalpel with the sciatic motor nerve of a frog he was dissecting, causing one of its legs to kick as in life.
Because the salty cytoplasm of the axon is electrically conductive, and because the myelin inhibits charge leakage through the membrane, depolarization at one node is sufficient to elevate the voltage at a neighboring node to the threshold for action potential initiation.
Action potentials are measured with the recording techniques of electrophysiology.
www.guajara.com /wiki/en/wikipedia/a/ac/action_potential.html   (913 words)

  
  Action potential - Wikipedia, the free encyclopedia
An action potential is a wave of electrical discharge that travels along the membrane of a cell.
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).
Action potentials are only regenerated at the unmyelinated nodes of Ranvier which are spaced intermittently between myelinated segments.
en.wikipedia.org /wiki/Action_potential   (3403 words)

  
 Cardiac action potential - Wikipedia, the free encyclopedia
The resting membrane potential is the difference in ionic charge across the membrane of the cell during phase 4 of the action potential.
Once the cell is electrically stimulated (typically by an electric current from an adjacent cell), it begins a sequence of actions involving the influx and eflux of multiple cations and anions that together produce the action potential of the cell, propogating the electrical stimulation to the cells that lie adjacent to it.
This phase of the action potential is associated with diastole of the chamber of the heart.
en.wikipedia.org /wiki/Cardiac_action_potential   (1098 words)

  
 Action potential   (Site not responding. Last check: )
An action potential is the local membrane potential created as a nerve impulse is They set the pace of thought and constrain the sizes of evolving anatomies and centralized control and coordination of organs and tissues.
Typically action potential initiation occurs a synapse but may occur anywhere along the In his discovery of "animal electricity " Luigi Galvani elicited an action potential through contact his scalpel with the sciatic motor nerve of a frog he dissecting causing one of its legs to as in life.
Action potentials (APs) are measured with the techniques of electrophysiology.
www.freeglossary.com /Action_potential   (963 words)

  
 Action potential -   (Site not responding. Last check: )
Action potentials carry fast internal messages between tissues, and are an essential feature of animal life.
An action potential is a rapid swing in the polarity of the membrane potential from negative to positive and back, the entire cycle lasting a few milliseconds.
The potential difference (a charge) which exists across the cell surface membrane of all cells is usually, as in the case of nerve cells, negative inside the cell with respect to the outside.
psychcentral.com /psypsych/Action_potential   (3380 words)

  
 Action Potential   (Site not responding. Last check: )
An action potential is caused by positive ions moving in and then out of the neuron at a certain spot on the neuron membrane.
An action potential is initiated by a stimulus above a certain intensity or threshold.
This single action potential acts as a stimulus to neighbouring proteins and initiates an action potential in another part of the neuron.
www.tvdsb.on.ca /westmin/science/sbioac/homeo/action.htm   (182 words)

  
 Neuroscience: A Journey Through the Brain - The Action 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.
An action potential travels only in one direction; it cannot turn back on itself because the membrane behind it is still refractory due to the inactivation of sodium channels.
www.ualberta.ca /~neuro/OnlineIntro/NeuronAP.htm   (748 words)

  
 Cardiac action potential: Facts and details from Encyclopedia Topic   (Site not responding. Last check: )
The cardiac action potential is the electrical activity of the individual cells of the electrical conduction system of the heart heart quick summary:
*in the context of biological membranes, the reversal potential of a particular ion species is the membrane voltage at which there is no net flow of ions from...
The standard model used to understand the cardiac action potential is the action potential of the ventricular myocyte myocyte quick summary:
www.absoluteastronomy.com /encyclopedia/c/ca/cardiac_action_potential.htm   (2315 words)

  
 Action Potential - Search Results - MSN Encarta
Action Potential, momentary change in the electrical charge stored on the surface of a nerve or muscle cell.
Deterrence, in international relations, the policy of discouraging hostile action by a potential aggressor.
- electrical signal associated with nerve impulse: a temporary change in electrical potential that occurs between the inside and the outside of a nerve or muscle fiber when a nerve impulse is transmitted
encarta.msn.com /Action_Potential.html   (189 words)

  
 Action Potentials - The Nerve Impulse   (Site not responding. Last check: )
Caused by an inflow of chloride or outflow of potassium ion, the transmembrane potential has moved away from threshold (the transmembrane potential is more negative) and now requires a stronger stimulus for there to be an adequate generator or an action potential.
The earliest part of the action potential curve is called the absolute refractory period, meaning the neuron cannot respond in any way that will change the shape of the curve during this time.
At resting potential proper, the action potential ends, and the membrane is capable of responding to a minimal stimulus.
sky.bsd.uchicago.edu /lcy_ref/synap/Action.html   (6024 words)

  
 What is an action potential?   (Site not responding. Last check: )
Fundamentally, the action potential is a change in a neuron's cellular membrane electrical potential that usually propagates in a wave-like manner down the axon of a neuron.
The action potential provides a means by which information can be transmitted relatively quickly over long distances in the nervous system, and the mechanism by which it is produced is similar in all known neurons.
One of the striking characteristics of the action potential is its all-or-none nature.
www.bio.brandeis.edu /biomath/mike/AP.html   (174 words)

  
 Reference.com/Encyclopedia/Action potential
Residing in and spanning the membrane, these proteins sense and respond to changes in transmembrane potential (see http://www.flwellpublishing.com/matthews/channel.html for an illustration).
In his discovery of "animal electricity," Luigi Galvani made a leg of a dead frog kick as in life by touching a sciatic nerve with his scalpel, to which he had inadvertently transfered a negative, static-electric charge.
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.reference.com /browse/wiki/Action_potential   (1221 words)

  
 action potential
The influx of positive charge into the axon during the generation of an action potential leads to the depolarization of adjacent membrane.
Subsequent action potential generation occurs across the membrane in front of the impulse, but not in back of it because of the refractory period.
Action potentials are generated only at the nodes of Ranvier; between the nodes, there is passive spread of potential.
www.du.edu /~kinnamon/3640/actionpotential/ap1.html   (615 words)

  
 Steve's place - Plant Action Potentials   (Site not responding. Last check: )
Action potentials are usually started (initiated) by a fall in the membrane potential below a threshold value.
Action potentials were first detected in plants showing rapid movements (thigmonastic plants): such as Dionaea muscipula (Venus flytrap), Drosera spp.
When the trigger hairs are stimulated, an action potential (mostly involving calcium ions) is generated, which propagates across the lobes and stimulates cells in the lobes and in the mibrib between them.
www.steve.gb.com /science/plant_action_potentials.html   (1351 words)

  
 Action potential   (Site not responding. Last check: )
They also actively generate and propagate action potentials through their membrane, allowing communication from one part of the cell to another and (subsequent to transmitter release) from one cell to another.
In real life, this would be done by generation of excitatory postsynaptic potentials (EPSPs), i.e., by the actions of neurotransmitters on ligand-gated ion channels or by activation of sensory receptors, etc. In this experiment, you'll depolarize the model cell by injecting current and observing the resulting change in membrane potential.
The effects of local anaesthetics on action potential production would be more obvious if more action potentials were being produced in response to the current step, which means that the cell has to be capable of repolarizing more completely.
www.d.umn.edu /~jfitzake/Lectures/6061IonChannelPhysiology/ActionPotential.htm   (784 words)

  
 Ectopic Action Potential Web-Page | Ectopic Action Potential Articles   (Site not responding. Last check: )
Cardiac resting potential, excitation threshold and action potential in the context.
Their clinical usefulness the thromboembolic potential of the estrogens is of particular concern.
Pools of axons as a consequence of ectopic action potential generation in the axons of principal cells.
www.ectopic-pregnancy-online.info /ectopic-action-potential.html   (922 words)

  
 Brain Explorer - Neurological Control - Action Potential   (Site not responding. Last check: )
Resting neurons have a negative membrane potential, caused by a steady outflow of potassium ions and an impermeability to sodium ions, and the action potential
, depolarisation initiates the action potential and causes a transient change in the membrane that briefly switches its permeability from that allowing the passage of potassium ions to that allowing the passage of sodium ions.
The falling phase of the action potential is caused by the subsequent closing of the sodium channels, which reduces the sodium influx, and by the opening of the voltage-gated potassium channels which allows increased efflux of potassium ions from the cell, to restore the negative resting membrane potential.
www.brainexplorer.org /neurological_control/Neurological_Action_potential.shtml   (237 words)

  
 Action Potentials   (Site not responding. Last check: )
Sodium conductance causes the rise in the action potential, while a potassium conductance causes a restoration of the potential.
Depolarization is any time the membrane potential goes to a more positive value than resting potential, while hyperpolarization is any time the membrane potential dips to a more negative value than resting potential.
An action potential is an action potential, and it either occurs or it doesn't.
faculty.stcc.edu /AandP/AP/AP1pages/nervssys/unit11/action.htm   (1104 words)

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