Hence, an arrow which bends less is said to have more spine. In order to strike consistently, a group of arrows must be similarly spined. Center-shot bows, in which the arrow passes through the central vertical axis of the bow riser, may obtain consistent results from arrows with a wide range of spines.
Definition of MELATONIN. : a vertebrate hormone that is derived from serotonin, is secreted by the pineal gland especially in response to darkness, and has been linked to the regulation of circadian rhythms.See melatonin defined for kids.ADVERTISEMENT. Greek melas black + -tonin (as in serotonin).efinition of MELATONIN. : a vertebrate hormone that is derived from serotonin, is secreted by the pineal gland especially in response to darkness, and has been linked to the regulation of circadian rhythms. See melatonin defined for kids. ADVERTISEMENT. Greek melas black + -tonin (as in serotonin).
Serotonin (also called 5-HT) is a neurotransmitter that is produced from tryptophan. Although serotonin is only produced by a small number of neurons (1000's), each of those neurons innervates as many as 500,000 other neurons (3, 12).rolonged use of MDMA results in destruction of serotonergic neurons in the brain (4, 5). Because of the similarities between ecstasy 'trips' and LSD 'trips,' it can be concluded that they must activate a similar pathway, i.e. the serotonergic pathway. Several theories of the mechanism of LSD have been postulated.