HMB200H1 Chapter Notes - Chapter 5: Internal Resistance, Autoreceptor, Potassium Channel
1 May 2014
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They allow the direct transfer of ionic current from one cell to the next: they occur at specialized sites called gap junctions. At a gap junction, the membranes of two cells are separated by only about 3 nm: this narrow gap is spanned by clusters of special proteins called connexins. 6 connexins combine to form a channel called a connexon: 2 connexons combine to form a gap function channel allowing ions to pass directly from the cytoplasm of one cell to the cytoplasm of the other. The pore of most gap junction channels is relatively large: its diameter is about 1-2 nm. In invertebrate species, such as the crayfish, electrical synapses are sometimes found between sensory and motor neurons in neural pathways mediating escape reflexes. This current causes a postsynaptic potential (psp) in the second neuron. This is an example of synaptic integration.
