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| | Action potential - Wikipedia, the free encyclopedia |
 | | The action potential, as a method of long-distance communication, fits a particular biological need seen most readily when considering the transmission of information along a nerve axon. | | | A basic RC circuit superimposed on an image of a membrane bilayer shows the relationship between the two. | | | The squid giant axon controls the muscle contraction associated with the squid's predator escape response. |
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http://en.wikipedia.org/wiki/Action_potential
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| | 16 Action Potential |
| | The resulting action potential is then recorded at a point immediately adjacent to the point of stimulation and at a second point some distance down the axon. | | | Consequently, the action potential radiates away from the point of stimulation, and does not move back toward it. | | | Refractoriness of voltage-gated Na channels permits unidirectional propagation of action potentials. |
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http://human.physiol.arizona.edu/sched/cv/wright/16action.htm
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| | action potential |
| | Conformational changes in the voltage-dependent Na channel constitute the basis of the action potential. | | | If this depolarization exceeds a threshold value then a rapid regenerative opening of many other Na channels follows, resulting in the depolarizing phase of an action potential. | | | The opening of a few Na channels leads to an initial depolarization. |
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http://www.du.edu/~kinnamon/3640/actionpotential/ap1.html
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| | Action Potentials - The Nerve Impulse |
| | This means you can change the transmembrane potential by that many millivolts. | | | A change in voltage of +20 mV was sufficient to stimule its transformation. | | | As you set the stimulator to deliver -5, 5, and 10 mV stimuli, you would see little or no change on your oscilloscope screen. |
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http://sky.bsd.uchicago.edu/lcy_ref/synap/Action.html
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| | NS Lecture 15: Action Potential |
| | The rapid "upstroke" of the depolarization was associated with a dramatic increase in Na conductance, whereas the "downstroke" of the event was associated with a slower, more prolonged increase in K conductance. | | | During this period, it takes a larger than normal stimulus to recruit the necessary number of channels to fire an action potential from the reduced pool of available channels; this period defines the relative refractory period. | | | At this potential, a population of voltage-gated Na channels began to open, thereby increasing the P |
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http://human.physiol.arizona.edu/SCHED/CV/Wright/15action.htm
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| | A Brief Introduction to the Brain:Action Potential |
| | This balance changes, however, when the cell is depolarized sufficiently to trigger an action potential. | | | This positive feedback cycle, develops exponentially driving the membrane potential toward the positive values. | | | The increase in depolarization causes more voltage gated Na channels to open, resulting in a greater influx of positive charge, which accelerates the depolarization still further. |
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http://ifcsun1.ifisiol.unam.mx/Brain/action.htm
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| | Action potential |
| | The first step is to try to get the voltage-dependent Na channels to open, which means you have to depolarize the cell. | | | To see what the effect of the delayed rectifier channels alone is, turn off the voltage-gated Na channels gNa = 0, and view the results . | | | Why does the action potential repolarize when no voltage-dependent K |
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http://www.d.umn.edu/~jfitzake/Lectures/6061IonChannelPhysiology/ActionPotential.htm
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| | Action Potential |
| | During the depolarization phase of the action potential the inside of the neuron is becoming less negative. | | | Therefore, if any movement of potassium were to occur it would make the inside of the neuron even more negative. | | | The action potential is the basic unit of function in the neuron. |
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http://www.cwru.edu/dental/web/neuro/ap.html
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| | Lecture 29 |
| | All of the nerve phenomena we have discussed can be explained by the opening and closing of ion channels for Na and K | | | Like a burning fuse: the heat of the burning section is sufficient to cause the next section of fuse to start burning | | | These channels are slower than the Na channels, so Na has the initial advantage, but later K kicks in to bring things back to normal |
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http://members.aol.com/BearFlag45/Biology1A/LectureNotes/lec29.html
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| | Lecture 7 |
| | Depolarization also triggers opening of K+ channels, but they begin to open slightly later than Na+ channel, so that peak flow of Na+ into cell precedes peak flow of K+ out of it, efflux of K+ from cell becomes significant just as Na+ influx reaches its peak, and Na+ channels have begun to close | | | Pore opens when molecule undergoes conformational change so that gate changes in position and pore no longer occluded. | | | Membrane then repolarizes regaining its resting, interior negative condition |
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http://soma.npa.uiuc.edu/courses/bio303/Ch5.html
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| | The Nerve Action Potential |
| | Many other cells have far more complicated action potentials, but all behave according to the general principles described here. | | | The stimulus can be changed to extend or shorten the prodromal phase. | | | Determine the relationship between each current and the various phases of the action potential. |
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http://physiology.umc.edu/Teaching/VSMLABS/VSMLABS.HTM
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| | Cardiac action potential - Wikipedia, the free encyclopedia |
| | Phase 1 of the action potential is due to closure of the fast Na channels. | | | This phase of the action potential is associated with diastole of the chamber of the heart. | | | During phase 3 of the action potential, the K |
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http://en.wikipedia.org/wiki/Cardiac_action_potential
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| | Action Potential |
| | Zachariou et al., An essential role for deltaFosB in the nucleus accumbens in morphine action | | | Brankatschk & Dickson, Netrins guide Drosophila commissural axons at short range | | | Action Potential is a blog by the editors of Nature Neuroscience â“ a forum for our readers, authors, and the entire neuroscience community. |
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http://blogs.nature.com/nn/actionpotential/atom.xml
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| | Neuroscience for Kids - Action Potential |
| | If the neuron does not reach this critical threshold level, then no action potential will fire. | | | Neuroscientists use other words, such as a "spike" or an "impulse" for the action potential. | | | This means that some event (a stimulus) causes the resting potential to move toward 0 mV. |
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http://staff.washington.edu/chudler/ap.html
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| | Action Potential |
| | During this time (~ 1 msec), the Na+ and K+ Channels cannot be opened by a stimulus. | | | The stimulus could be a pin prick, light, heat, sound or an electrical disturbance in another part of the neuron. | | | This single action potential acts as a stimulus to neighbouring proteins and initiates an action potential in another part of the neuron. |
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http://www.tvdsb.on.ca/westmin/science/sbioac/homeo/action.htm
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| | Action Potential Facts |
| | is an "explosive" example of positive feedback, where depolarization to threshold potential causes further depolarization. | | | The value of this potential is -70 millivolts. | | | One of these gates allows Na to diffuse back through the membrane to allow depolarization during the action potential (sse below). |
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http://home.earthlink.net/~dayvdanls/physio_nerve.html
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| | [No title] |
| | Please use the slider bars to make adjustments in the parameters and observe the ways in which they affect the different phases of the action potential. | | | Hodgkin and Huxley developed a set of equations to describe how a cell produces an action potential upon stimulation, through interactions of voltage-dependent Na and K | | | The activation of the Na channels in turn accelerates the depolarization process, producing the rising phase of the action potential. |
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http://www.neurophys.wisc.edu/~cai/software/hhsimu/hhsimu.html
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| | Lecture 13: Electrical communication - the action potential |
| | Describe the role of voltage-gated channels and positive feedback in the action potential. | | | Tutorial: Overview of the factors responsible for the resting potential and action potential | | | Both these texts give similar and detailed explanations of the action potential, so it's a good idea to read one of them, but don't bother reading both: |
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http://www.columbia.edu/cu/biology/courses/c2006/lectures02/lect13.02.html
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| | Action potential animation |
| | Notice how the action potential involves an influx of Na+ which causes a region of positive charge that then opens nearby Na+ channels. | | | This "chain reaction" is how the action potential moves down the axon. | | | The following animaltion should help you to see how the action potential moves along the axon's membrane. |
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http://intro.bio.umb.edu/111-112/112s99Lect/neuro_anims/a_p_anim1/WW1.htm
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| | Psyc. 358 Lecture - Action Potential I |
| | at other segments, stimulus is current sourced by approaching AP in sensory neurons, depolarization is coupled to the action of a stimulus, such as the stretch of a muscle or the deformation of the skin | | | , positive feedback sets in, and an action potential is initiated | | | the peak of the action potential is determined not by the depolarizing stimulus but rather by |
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http://artsci-ccwin.concordia.ca/psychology/psyc358/Lectures/actpotent1.htm
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| | Action Potential |
| | , affects mainly on APD and resting potential. | | | increases, the changes in action potential are mainly in repolarization phase, thus resting potential becomes less negative and APD decreases; the changes in depolarization and plateau phased are minimum. | | | shows conductance of different ion channels during the course of action potential. |
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http://www.cc.utah.edu/~qn5349/ep/node14.html
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| | The Action Potential |
| | The Na channels close when the voltage peaks, and K channels open; these vent K into the interstitial fluid. | | | The result is increased difficulty in both mental and motor functions. | | | The membrane potential changes which occur during nerve impulse propagation are collectively called the "action potential". |
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http://www.rwc.uc.edu/koehler/biophys/4d.html
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| | Saltatory Conduction of APs |
| | If this axon innervated muscle, that muscle can no longer be controlled. | | | This is the type of conduction of action potentials that I described during our class this week. | | | We will refer to these methods as action potential conduction for unmyelinated axons, and saltatory conduction for myelinated axons. |
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http://distance.stcc.edu/AandP/AP/AP1pages/nervssys/unit11/saltator.htm
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| | Propagation of an Action Potential |
| | (B) shows the changes in the Na+ channels and the current flows (brown arrows) that give rise to the traveling disturbance of the membrane potential. | | | Note that the action potential does not weaken as it travels. | | | An action potential can only travel away from the site of depolarization because Na+-channel inactivation prevents the depolarization from spreading backward. |
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http://www.accessexcellence.org/AB/GG/action_Potent.html
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| | Action Potential |
| | The Rising Phase of the Action Potential: A Positive Feedback | | | The Rising Phase of the Action Potential: A Positive Feedback Loop. | | | Hyperpolarization = Movement of the membrane potential to a point more |
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http://www.ux1.eiu.edu/~cfklm/zoo2001/ap20.html
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| | Action Potential |
| | Nerve action potentials are the electrical signals sent out by the body to control bodily processes such as muscular movement. | | | As a nerve action potential propagates along a neuron it goes through several phases which are shown in the graph below. | | | This means that a nerve action potential will not occur unless the depolarization threshold is met. |
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http://www.shodor.org/Hodgkin/pot.html
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| | action potential - multiple sclerosis encyclopaedia |
| | 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. | | | As the action potential passes, the potassium channels open and the sodium channels close. | | | The action potential is an explosive release of charge between a nerve cell (neuron) and its surroundings. |
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http://www.mult-sclerosis.org/actionpotential.html
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| | Brain Explorer - Neurological Control - Action Potential |
| | This produces the rising phase, or upshoot, of the action potential, and means that the membrane potential becomes positive for a short time. | | | 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. | | | In most nerve cells, action potentials are followed by a transient hyperpolarisation. |
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http://www.brainexplorer.org/neurological_control/Neurological_Action_potential.shtml
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| | Excitable Cells |
| | The resulting IPSP may also prevent what would otherwise have been effective EPSPs from triggering an action potential. | | | The action potential is usually generated in the axon hillock. | | | This is the action potential (In neurons, the action potential is also called the nerve impulse.) |
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http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/E/ExcitableCells.html
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| | action potential - definition of action potential by the Free Online Dictionary, Thesaurus and Encyclopedia. |
| | A momentary change in electrical potential on the surface of a nerve or muscle cell that takes place when it is stimulated, especially by the transmission of a nerve impulse: Stimulating a nerve fiber causes an action potential to spread across the nerve cell, making it contract. | | | This information should not be considered complete, up to date, and is not intended to be used in place of a visit, consultation, or advice of a legal, medical, or any other professional. | | | action potential - the local voltage change across the cell wall as a nerve impulse is transmitted |
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http://www.thefreedictionary.com/action+potential
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| | Basic Neural Processes Tutorials |
| | Study and Check your Knowledge of the Human Brain. | | | Review of Physical Factors Involved in the Action Potential. |
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http://psych.hanover.edu/Krantz/neurotut.html
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| | The Action Potential |
| | The word potential refers to the fact that there is a potential for change here. | | | The myelin sheath around many axons speeds up this process considerably: Instead of one tiny segment triggering action at the very next little segment, the changes "jump" from one gap in the sheath to the next. | | | This is called saltatory conduction, from the Latin word for "jump" (also seen in words like somersault). |
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http://www.ship.edu/~cgboeree/actionpot.html
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| | action potential |
| | The falling phase of the action potential is caused by the closing of sodium channels and the opening of potassium channels, which allows a charge approximately equal to that brought into the cell to leave in the form of potassium ions. | | | The Nobel Prize for Physiology or Medicine was awarded in 1963 to A.L. Hodgkin, A.F. Huxley, and Sir John Eccles for formulating these ionic mechanisms involved in nerve cell activity. | | | Before stimulation, a neuron or muscle cell has a slightly negative electric polarization; that is, its interior has a negative charge compared with the extracellular fluid. |
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http://search.eb.com/nobel/micro/4_24.html
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| | Action Potential |
| | The action potential in one localized area is enough to stimulate the opening of a Na gate in a nearby region. | | | What is unique about nerve and muscle cells that allow them to have action potentials? | | | The fact that the concentration of Na - Cl is greater outside a cell than inside means that there is more positive charge outside the cell than inside. |
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http://www.mrs.umn.edu/~goochv/AnimalPhys/actionpotential/actionpot.html
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| | Spike potential |
| | Only a very strong stimulus can stimulate the neuron during this phase. | | | If a stimulus arrives during this phase of the potential it can not stimulate the neuron. | | | If voltage change surpasses this value, the depolarization automatically goes to its maximum value. |
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http://www.yorku.ca/eye/spike.htm
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| | Action potential figures |
| | These following images should help you to see how the action potential moves along the axon's membrane. | | | Take a look at the animated figure (16 k) which includes these imagese in motion (it may not work on all web browsers). |
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http://intro.bio.umb.edu/111-112/112s99Lect/neuro_anims/a_p_anim1/WW3.htm
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| | Action Potential Science Experience |
| | Penn State is committed to affirmative action, equal opportunity, and the diversity of its workforce. | | | Please e-mail us with your questions, comments, or suggestions at |
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http://www.sciencecamps.psu.edu
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| | Action Potential |
| | The membrane potential approaches the equilibrium potential for Sodium (E Na) | | | Conduction velocities vary over a range of 100x with the most rapid being faster than 100 m/sec. | | | Channels open and the membrane permiability to sodium is suddenly increase greatly. |
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http://retina.anatomy.upenn.edu/~lance/Physio/potential_action.html
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| | Shockwave |
| | teaches relation between action potential at different points along axon | | | physiology, nervous system, neuron, axon, action potential, propagation | | | click on any electrode to trigger an action potential |
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http://lessons.harveyproject.org/development/nervous_system/cell_neuro/action_potential/propagation.html
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| | action potential |
| | Just about every artist at Potential Wreckords was either in or inspired by Action Potential. | | | Five years after the demise of the band, we've finally retired the old Action Potential web site. | | | Last modified 08/07/04, o v e r l o r d @ c h e r k . c o m. |
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http://www.cherk.com/actionpotential
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| | Action Potential: Building Community One Click At A Time |
| | Action Potential: Building Community One Click At A Time | | | Copyright © 2001-2006 by Action Potential Networks, Inc.. | | | Use of this Website signifies your agreement to the Terms Of Service and Privacy Policy |
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http://www.actionpotential.org
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