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 widely occurring neurotransmitter-like compound derived primarily from the pineal gland. It is also produced in a number of other areas, for example the gastrointestinal tract.Once labeled as a master hormone, it has been found to be involved in numerous aspects of biological and physiologic regulation.elatonin is a widely occurring neurotransmitter-like compound derived primarily from the pineal gland. It is also produced in a number of other areas, for example the gastrointestinal tract.