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).
Melatonin is a hormone produced in the brain by the pineal gland from the amino acid tryptophan. The production and release of melatonin are stimulated by darkness and decreased by light, suggesting that melatonin is involved in circadian rhythm (the internal body clock) and regulation of diverse body functions.elatonin is a hormone produced in the brain by the pineal gland from the amino acid tryptophan. The production and release of melatonin are stimulated by darkness and decreased by light, suggesting that melatonin is involved in circadian rhythm (the internal body clock) and regulation of diverse body functions.