Chemical synapse cells, known as a gap junction. At gap junctions, cells approach within about 3.5 nm of each other, rather than the 20 to 40 nm distance that separates cells at chemical synapses. As opposed to chemical synapses, the postsynaptic potential in electrical synapses is not caused by the opening of ion channels by chemical transmitters, but rather by direct electrical coupling between both neurons. Electrical synapses are faster than chemical synapses. Electrical synapses are found throughout the nervous system, including in the retina, the reticular nucleus of the thalamus, the neocortex, and in the hippocampus. While chemical synapses are found
Drug delivery to the brain Drug delivery to the brain Drug delivery to the brain is the process of passing therapeutically active molecules across the blood–brain barrier for the purpose of treating brain maladies. This is a complex process that must take into account the complex anatomy of the brain as well as the restrictions imposed by the special junctions of the blood–brain barrier. The blood–brain barrier is formed by special tight junctions between the epithelial cells that surround the brain tissue. All tissue is separated by this layer of epithelial cells, however only the brain epithelial cells have these tight junctions that do not