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).
Photo Credit Design Pics/Design Pics/Getty Images. Serotonin and melatonin are both hormones that regulate various human functions such as sleep, appetite and mood. Serotonin, which is produced in the body, is known as a neurotransmitter; this means it is responsible for sending messages between nerve cells.hoto Credit Design Pics/Design Pics/Getty Images. Serotonin and melatonin are both hormones that regulate various human functions such as sleep, appetite and mood. Serotonin, which is produced in the body, is known as a neurotransmitter; this means it is responsible for sending messages between nerve cells.