Synapse with serotonin and melatonin
Illustration of a synapse. Synapses are contact points between nerves or nerves and other cells. There are electrical or chemical synapses, the picture shows a chemical synapse. The upper part shows the terminal axon of a nerve cell, which contains vesicles filled with transmitters, in this case serotonin. When a stimulus arrives, the vesicles fuse with the membrane, releasing their neurotransmitters into the synaptic cleft - which is very thin, so that the transmitters quickly get to the receptors of the dendritic postsynaptic density of the following cell, where they cause a stimulus. Lack of serotonin can cause depression or anxiety. Melatonin is produced by the pineal gland (epiphysis) out of serotonin. The hormone melatonin regulates the circadian rhythm.
