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).
These are hormones derived from fats or lipids such as linoleic acid, arachidonic acid and the phospholipids. The main class of lipid-derived hormone is the steroids which are derived from cholesterol and the eicosanoids. Steroid hormones include testosterone, estrogen and cortisol.Testosterone and estrogen are important regulators of reproductive function, secreted by both the testes and the ovaries.hese are hormones derived from fats or lipids such as linoleic acid, arachidonic acid and the phospholipids. The main class of lipid-derived hormone is the steroids which are derived from cholesterol and the eicosanoids. Steroid hormones include testosterone, estrogen and cortisol.