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Neurons are diverse with respect to morphology and function.
Thus, not all neurons correspond to the stereotypical motor neuron with dendrites and myelinated axons that conduct action potentials.
Metabotropic receptors on the other hand activate second messenger cascade systems that result in the opening of ion channel located some place else on the same postsynaptic membrane.
Although slower than ionotropic receptors that function as on-and-off switches, metabotropic receptors have the advantage of changing the cell's responsiveness to ions and other metabolites, examples being gamma amino-butyric acid (inhibitory transmitter), glutamic acid (excitatory transmitter), dopamine, norepinephrine, epinephrine, melanin, serotonin, melatonin, and substance P.
Several techniques such as intracellular recording, patch-clamp, and voltage-clamp technique, pharmacology, confocal imaging, molecular biology, two photon laser scanning microscopy and Ca2 imaging have been used to study activity at the cellular level.
There are several underlying mechanisms that cooperate to achieve synaptic plasticity, including changes in the quantity of neurotransmitters released into a synapse and changes in how effectively cells respond to those neurotransmitters.
An action potential can be divided into several sequential phases: threshold, rising phase, falling phase, undershoot phase, and recovery.
Following several local graded depolarizations of the membrane potential, the threshold of excitation is reached, voltage-gated sodium channels are activated, which leads to an influx of Na ions.
The Hodgkin–Huxley model of an action potential in the squid giant axon has been the basis for much of the current understanding of the ionic bases of action potentials.
Briefly, the model states that the generation of an action potential is determined by two ions: Na and K .
As Na ions enter the cell, the membrane potential is further depolarized, and more voltage-gated sodium channels are activated.