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All or nothing response of an action potential (AP), refers simply to the fact that an AP will either occur, or not. There is no gradient, no half APs or double APs. The only option is AP, or no AP. Like in computer binary, the response is either 1 (an AP) or 0 (no AP).

All the factors trying to induce (or inhibit) an action potential (i.e other action potentials, EPSPs and IPSPs) add up (summate) at the axon hillock, (aka the trigger zone). Here, if the stimulation is big enough an action potential will occur. If the stimulation is not big enough, no action potential occurs.

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15y ago
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14y ago

Neurons in their resting state are normally fairly dormant, the "none" meaning they don't pass current along their axons because their ion channels are closed.

A small, threshold amount of current into a neuron will trigger a massive cascade of ion flow, the "all". It's like a dam breaking or putting your tongue on a car battery, where prior build up of potential is released in a large surge.

The usual context for this phrase is *neurons* vs. *nerves*. Neurons are (relatively) "all or none", nerves aren't. Nerves (tissue) are composed of many different neurons (cells), many of which have different thresholds and propagation characteristics. Stimulating a nerve generally causes only part of the individual neurons to be activated -- a "graded" response.

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12y ago

The action potential is an all-or-none phenomenon, it either happens completely or doesn't happen at all. this means, the properties of the action potential are independent of the relative strength of the depolarizing stimulus as long as that stimulus exceeds threshold.

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Q: Why are action potentials said to be all or none?
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Action potentials originate at the?

Action potentials are how nerve impulses are transmitted from neuron to neuron. An action potential is formed when a stimulus to the nerve cell causes the membrane to depolarize and open all of its sodium ion channels toward the threshold potential.


Action potentials can be generated by virtually all cells of the body because all cells possess cell membranes?

No


Is an action potential is a phenomenon that either happens completely or doesn't happen at all?

The action potential is an all-or-none phenomenon.


What does a conduction velocity of an action potential depend on?

An action potential does not have a conduction velocity. Rather, it makes sense to measure the conduction velocity of nerves or nerve cells and this is usually done in metres per second (m/s.). An action potential is characterised as "an all or none response". This means you cannot alter the characteristics of an action potential in a given nerve cell. If you get a nerve cell and manage to get it to threshold, produce and measure an action potential 1000 times or more at the exact same point on the cell, the action potential you measure will not change in timing or amplitude. Information travels down a nerve cell through action potentials. But it is not one action potential that travels the whole length of the axon. Instead what happens is that one action potential causes the next bit of the nerve cell to reach threshold and therefore creates an entirely new action potential. So you actually need multiple action potentials to happen along a nerve cell to send information down it. We call this "propagation of action potentials" since each action potential produces a new one. More properly, it is referred to as "saltatory action potential conduction". Conduction velocity is basically a measure of how quickly we can produce a series of action potentials to travel the distance of the nerve cell axon. Since action potentials only happen at each "Node of Ranvier", then the longer the distance between each node (internodal distance), the faster the conduction velocity of a nerve cell. Since the internodal distance is positively correlated with myelin thickness, more thickly myelinated nerve cells have faster conduction velocities. The thickest and fastest nerve cells are motor neurones and Ia fibres from muscle spindles with a diameter of 12-20 micrometres and a conduction velocity of 70-120 m/s. The thinnest/slowest are fibres used to convey slow pain (<1.5 micrometres and 0.5-2 m/s).


What principle states that the properties of the action potential are independent of the relative strength of the depolarizing stimulus?

the all-or-none principle

Related questions

Action potentials are generated within the axon according to the?

All-or-none principle


The all or none principle states that?

all stimuli great enough to bring the membrane to threshold will produce identical action potentials. :)


Are graded potentials the same as local potentials?

Postsynaptic potentials are changes in the membrane potential of the postsynaptic terminal of a chemical synapse. Graded potentials are changes in membrane potential that vary in size, as opposed to being all-or-none, and are not postsynaptic potentials.


What is the Difference between a weak stimulus and intense stimulus?

The FREQUENCY of action potentials that are conducted into the central nervous system serves as the code for the strength of the stimulus. This frequency code is needed because the amplitude of action potentials is constatnt (all or none). Acting through changes in action potential frequency, tonic receptors thus provide information about the relative intensity of a stimulus.


What is the composite recording of all nodal and myocardial action potentials?

Electrocardiogram (ECG or EKG)


Action potentials originate at the?

Action potentials are how nerve impulses are transmitted from neuron to neuron. An action potential is formed when a stimulus to the nerve cell causes the membrane to depolarize and open all of its sodium ion channels toward the threshold potential.


What is the difference between a compound action potential and a single action potential?

Single action potentials follow the "all or none" rule. That is, if a stimulus is strong enough to depolarize the membrane of the neuron to threshold (~55mV), then an action potential will be fired. Each stimulus that reaches threshold will produce an action potential that is equal in magnitude to every other action potential for the neuron. Compound action potentials do not exhibit this property since they are a bundle of neurons and have different magnitudes of AP's. Thus compound action potentials are graded. That is, the greater the stimulus, the greater the action potential.


Action potentials can be generated by virtually all cells of the body because all cells possess cell membranes?

No


How does the end plate potential differ from a EPSP on a post synaptic cell?

End plate potential is the change in potential from neurotransmitters. It can be excitatory or inhibitory. If the action potential wants to continue, it will be excitatory and vice versa. It can be additive, if more action potentials are fired it will increase the end plate potential. An action potential is an all or none response. It will either proceed or it will not proceed depending on the terms of the threshold. It cannot be additive, because there is an absolute refractory period where no additional action potentials can be fired.


Why does the frog sciatic nerve give a graded response?

The frog schiatic nerve gives a graded response because the nerve is a bundle of axons and not a single axon (thus it does not show the all or none response of an axon-either generating an action potential or not). If one axon is generating an action potential then a small nerve impulse is witnessed, if all axons are simultaneously generating action potentials then a large nerve impulse is witnessed. Thus the nerve impulse is graded (it can be none, small, medium, large, larger, maximal).


Do action potentials always have the same amplitude and the same duration?

Yes, this is due to the all or nothing law that neurons follow: "an excitable membrane either responds to a stimulus with a maximal action potential that spreads nondecrementally throughout the membrane, or it does not respond with an action potential at all." "


What is the money cheat to action all stars?

there is none