In the third lecture we talked about synapses and synaptic transmissions. There are two kind of transmissions, electrical and chemical. What was new, were especially the electrical synapses. They occur at gap junctions (which then again occur between cells in nearly every part of the body). The speciality of electrical synapses is, that they allow direct transfer of ionic current from one cell to the next and they function bidirectionally (to both directions, unlike chemical synapses). Also, transmission at these is very fast, which is logical since they don’t require the electrical-chemical-electrical transformation that chemical synapses do. For what are these then needed for? They are important in locations, where normal function requires synchronized activity of neighboring cells.
The chemical synapses are only between neurons. Compared to electrical synapses, they are slow. It takes time to convert the electrical signal to a chemical signal in the synaptic cleft and then back to an electrical signal. In the chemical transmission the action potential opens Ca2+ channels in the axon terminals membrane which then again allows the vesicles to release the neurotransmitters to the synaptic cleft. These neurotransmitters either excite or inhibit the action potential in the postsynaptic cell depending on the neurotransmitter and the receptors of the postsynaptic membrane.
Additionally, in the exercise session of this week, we learned about neuroanatomy, which was highly interesting!
Alexandra & Alisa