Some neurons such as photoreceptor cells, for example, do not have myelinated axons that conduct action potentials.
Other unipolar neurons found in invertebrates do not even have distinguishing processes such as dendrites.
After neurotransmitters are synthesized, they are packaged and stored in vesicles.
These vesicles are pooled together in terminal boutons of the presynaptic neuron.
Neurons are cells that are specialized to receive, propagate, and transmit electrochemical impulses.
In the human brain alone, there are over eighty billion neurons.
These allow Ca2 ions to diffuse through these channels and bind with synaptic vesicles within the terminal boutons.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.Cellular neuroscience is the study of neurons at a cellular level.