närviühenduse

Närviühendus, also known as a synapse, is the specialized junction between two neurons where information is transmitted from one neuron to another. This communication typically occurs through chemical or electrical signals. Chemical synapses are the most common type, involving the release of neurotransmitters from the presynaptic neuron into the synaptic cleft. These neurotransmitters then bind to receptors on the postsynaptic neuron, causing a change in its electrical potential. Electrical synapses, on the other hand, allow for direct flow of ions between neurons through gap junctions, enabling faster transmission.

The process at a chemical synapse begins when an action potential arrives at the axon terminal of the presynaptic neuron. This triggers the opening of voltage-gated calcium channels, allowing calcium ions to enter the terminal. The influx of calcium causes synaptic vesicles containing neurotransmitters to fuse with the presynaptic membrane and release their contents into the synaptic cleft. Neurotransmitters diffuse across the cleft and bind to specific receptors on the postsynaptic membrane. This binding can either excite or inhibit the postsynaptic neuron, depending on the type of neurotransmitter and receptor involved.

Synaptic plasticity, the ability of synapses to strengthen or weaken over time, is crucial for learning and memory. This can occur through changes in the amount of neurotransmitter released, the number of receptors on the postsynaptic membrane, or alterations in the structure of the synapse itself. Dysfunctions in närviühendused are implicated in various neurological and psychiatric disorders, highlighting their fundamental importance in brain function.