what exactly is action potential. dont give me a link, i need it in laymen terms. what does it have to do w/?

Answer 1

Action potential is a property of excitable cells like nerve cells and muscle cells.
As you might be knowing the cell membranes have a potential difference across them, i.e. they have more positive ions on the outer side of the membrane than the inside. So the inside of the cell is negatively charged as compared to the outside, or it is 'polarised'. Because of the selective permeabilities of the cell membrane, ions cannot move freely across the membrane to equalise the charges.
Action potential is the reversal of the 'polarised' state of the cell membrane, that is the inside of the cell achieves a positive potential, even more positive than the outside potential. This is an instantaneous process. It takes place, usually when the cell is given a proper stimulation. And it is acheieved by facilitating the flow of positive ions inside the cell(which was negative w.r.t. outside) which is in turn made possible by changes in the permeability of the cell membrane.
As a result of action potential the internal milieu of the nerve/muscle cell changes for that instant and this serves as a 'start' to the cell machinary to perform the function it is intended to perform. For example a muscle cell will contract upon having an action potential, a nerve cell will transmit the signal further to another nerve or muscle or it will release some chemicals from its other end.
The action potential is over almost instantaneously, and the polarity of the cell membrane is restored immediately. This is all again brought about by changes in the cell permeability to various ions.

Answer 2

Much of what we know about how neurons work comes from experiments on the giant axon of the squid. This giant axon extends from the head to the tail of the squid and is used to move the squid's tail. How giant is this axon? It can be up to 1 mm in diameter - easy to see with the naked eye
Neurons send messages electrochemically. This means that chemicals cause an electrical signal. Chemicals in the body are "electrically-charged" -- when they have an electrical charge, they are called "ions." The important ions in the nervous system are sodium and potassium (both have 1 positive charge, +), calcium (has 2 positive charges, ++) and chloride (has a negative charge, -). There are also some negatively charged protein molecules. It is also important to remember that nerve cells are surrounded by a membrane that allows some ions to pass through and blocks the passage of other ions. This type of membrane is called semi-permeable.

Resting Membrane 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. Although the concentrations of the different ions attempt to balance out on both sides of the membrane, they cannot because the cell membrane allows only some ions to pass through channels (ion channels). At rest, potassium ions (K+) can cross through the membrane easily. Also at rest, chloride ions (Cl-)and sodium ions (Na+) have a more difficult time crossing. The negatively charged protein molecules (A-) inside the neuron cannot cross the membrane. In addition to these selective ion channels, there is a pump that uses energy to move three sodium ions out of the neuron for every two potassium ions it puts in. Finally, when all these forces balance out, and the difference in the voltage between the inside and outside of the neuron is measured, you have the resting 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. At rest, there are relatively more sodium ions outside the neuron and more potassium ions inside that neuron.

Action Potential
The resting potential tells about what happens when a neuron is at rest. An action potential occurs when a neuron sends information down an axon, away from the cell body. Neuroscientists use other words, such as a "spike" or an "impulse" for the action potential. The action potential is an explosion of electrical activity that is created by a depolarizing current. This means that some event (a stimulus) causes the resting potential to move toward 0 mV. When the depolarization reaches about -55 mV a neuron will fire an action potential. This is the threshold. If the neuron does not reach this critical threshold level, then no action potential will fire. 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. There are no big or small action potentials in one nerve cell - all action potentials are the same size. Therefore, the neuron either does not reach the threshold or a full action potential is fired - this is the "ALL OR NONE" principle.
Action potentials are caused by an exchange of ions across the neuron membrane. A stimulus first causes sodium channels to open. Because there are many more sodium ions on the outside, and the inside of the neuron is negative relative to the outside, sodium ions rush into the neuron. Remember, sodium has a positive charge, so the neuron becomes more positive and becomes depolarized. It takes longer for potassium channels to open. When they do open, potassium rushes out of the cell, reversing the depolarization. Also at about this time, sodium channels start to close. This causes the action potential to go back toward -70 mV (a repolarization). The action potential actually goes past -70 mV (a hyperpolarization) because the potassium channels stay open a bit too long. Gradually, the ion concentrations go back to resting levels and the cell returns to -70 mV.
Hope that answers it. You can also checks the links below for detailed info. The first one is a good animation to help you understand.

Answer 3

An action potential is an increase in electrical charge that moves through a cell (most often neurons, but also other cells like those in the heart for a simultaneous contraction signal) as the result of various ions moving into an out of the cell membrane. Basically, a cell is signaled (usually from another cell) which tells it to open up its sodium (Na+) ion channels. Due to the fact that sodium is present in much greater amounts outside the cell, it diffuses into the cell by these channels. Because sodium ions are positive in charge, the electrical potential of the cell in the area where it comes in becomes much greater. If this change is big enough (i.e. reaches "threshold"), an action potential arises in which this electrical charge difference in part of the cell moves down the rest of the cell. This is accomplished by opening more sodium ion channels in the other parts of the cell. As a result, the charge moves through the cell as an action potential much like a wire carries electricity. This electrical signal can be used to communicate over relatively long distances in the body.

Answer 4

although the name portrays that it is the ability to do something, it is actually a process that occurs. In a neuron a signal is transmitted from one end to the other by switching the charge on the membrane of the neuron. The movement of this charge from one end of the cell to the other is the action potential/

Answer 5

Action Potential is the ability of a cell to perform its function.

Answer 6

Action potentials are the electical impulses that transmit information along your nerve fibers (axons).