20 Facts About Action potentials


Action potentials occur in several types of animal cells, called excitable cells, which include neurons, muscle cells, and in some plant cells.

FactSnippet No. 1,097,786

Action potentials are generated by special types of voltage-gated ion channels embedded in a cell's plasma membrane.

FactSnippet No. 1,097,787

Action potentials are driven by channel proteins whose configuration switches between closed and open states as a function of the voltage difference between the interior and exterior of the cell.

FactSnippet No. 1,097,788

Action potentials are triggered when enough depolarization accumulates to bring the membrane potential up to threshold.

FactSnippet No. 1,097,789

The frequency at which a neuron elicits action potentials is often referred to as a firing rate or neural firing rate.

FactSnippet No. 1,097,790

Related searches


In contrast to passive spread of electric potentials, action potentials are generated anew along excitable stretches of membrane and propagate without decay.

FactSnippet No. 1,097,791

Action potentials are most commonly initiated by excitatory postsynaptic potentials from a presynaptic neuron.

FactSnippet No. 1,097,792

Rectifying channels ensure that action potentials move only in one direction through an electrical synapse.

FactSnippet No. 1,097,793

Therefore, action potentials are said to be all-or-none signals, since either they occur fully or they do not occur at all.

FactSnippet No. 1,097,794

The period during which action potentials are unusually difficult to evoke is called the relative refractory period.

FactSnippet No. 1,097,795

Action potentials potential generated at the axon hillock propagates as a wave along the axon.

FactSnippet No. 1,097,796

However, if a laboratory axon is stimulated in its middle, both halves of the axon are "fresh", i e, unfired; then two action potentials will be generated, one traveling towards the axon hillock and the other traveling towards the synaptic knobs.

FactSnippet No. 1,097,797

For example, action potentials move at roughly the same speed in a myelinated frog axon and an unmyelinated squid giant axon, but the frog axon has a roughly 30-fold smaller diameter and 1000-fold smaller cross-sectional area.

FactSnippet No. 1,097,798

In general, action potentials that reach the synaptic knobs cause a neurotransmitter to be released into the synaptic cleft.

FactSnippet No. 1,097,799

Muscle action potentials are provoked by the arrival of a pre-synaptic neuronal action potential at the neuromuscular junction, which is a common target for neurotoxins.

FactSnippet No. 1,097,800

The fundamental difference from animal action potentials is that the depolarization in plant cells is not accomplished by an uptake of positive sodium ions, but by release of negative chloride ions.

FactSnippet No. 1,097,801

Action potentials are found throughout multicellular organisms, including plants, invertebrates such as insects, and vertebrates such as reptiles and mammals.

FactSnippet No. 1,097,802

The integration of various dendritic signals at the axon hillock and its thresholding to form a complex train of action potentials is another form of computation, one that has been exploited biologically to form central pattern generators and mimicked in artificial neural networks.

FactSnippet No. 1,097,803

Study of action potentials has required the development of new experimental methods.

FactSnippet No. 1,097,804

The conduction velocity of action potentials was first measured in 1850 by du Bois-Reymond's friend, Hermann von Helmholtz.

FactSnippet No. 1,097,805