Neurons are one of the main types of cells within the nervous system. They allow communication between brain regions and neighboring neurons. A typical neuron has four distinct regions: the axon, which sends electrical and chemical signals to neighboring neurons; dendrites, which receive signals from axons; the cell body, which contains the nucleus and other important organelles; and the presynaptic terminal, which contain a vast array of neurotransmitters and receptors and are critical for neuronal communication.