Asked in BiologyPsychologyNervous SystemCell Biology (cytology)
What do the excitatory neurotransmitters do?
June 29, 2008 11:50PM
Exitatory neurotransmitters, such as acetylcholine and glutamate, bind as ligands to ligand-gated channel proteins. Once these neurotransmitters have binded to these transport proteins, the channel opens between the outside and inside of the cell. Once open, sodium (Na+) ions tend to rush into the cell from the outside along with the electrochemical gradient, because these ions want to go from high concentration and positive membrane charge to where there is a lower concentration of Na+ and a more negative membrane charge. This action depolarizes the membrane, meaning the difference in voltage between the inside and the outside of the cell membrane becomes less negative. Depolarization of the cell membrane increases the likelihood of firing an action potential down that neuron, opening calcium (Ca2+) channels in the synaptic terminals, causing an influx of calcium, which causes vesicles filled with neurotransmitters to fuse to the presynaptic membrane, releasing the neurotransmitters into the synapse, starting the whole process over again.