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An electrical synapse is an electrically conductive link between two abutting neurons that is formed at a narrow gap between the pre- and postsynaptic 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.
Each gap junction (sometimes called a nexus) contains numerous gap junction channels that cross the plasma membranes of both cells. [11] With a lumen diameter of about 1.2 to 2.0 nm, [2] [12] the pore of a gap junction channel is wide enough to allow ions and even medium-size molecules like signaling molecules to flow from one cell to the next, [2] [13] thereby connecting the two cells' cytoplasm.
[21] [22] In fact, gap junctions facilitate the direct flow of electrical current without the need for neurotransmitters, as well as small molecules like calcium. [23] Thus, the main advantage of an electrical synapse is the rapid transfer of signals from one cell to the next.
A diagram of the proteins found in the active zone. The active zone is present in all chemical synapses examined so far and is present in all animal species. The active zones examined so far have at least two features in common, they all have protein dense material that project from the membrane and tethers synaptic vesicles close to the membrane and they have long filamentous projections ...
This pool is larger than the readily releasable pool, but it takes longer to become mobilised. The reserve pool contains vesicles that are not released under normal conditions. This reserve pool can be quite large (~50%) in neurons grown on a glass substrate, but is very small or absent at mature synapses in intact brain tissue. [8] [9]
Neurons communicate with other cells via synapses, which are specialized connections that commonly use minute amounts of chemical neurotransmitters to pass the electric signal from the presynaptic neuron to the target cell through the synaptic gap. Neurons are the main components of nervous tissue in all animals except sponges and placozoans.
The gap junction had been shown to create a micro-environment between the two cells in the extracellular space or gap. This portion of extracellular space was somewhat isolated from the surrounding space and also bridged by what we now call connexon pairs, which form even more tightly sealed bridges that cross the gap junction gap between two ...
A dendritic spine (or spine) is a small membrane protrusion from a neuron's dendrite that typically receives input from a single axon at the synapse.Dendritic spines serve as a storage site for synaptic strength and help transmit electrical signals to the neuron's cell body.