d) Growth Hormone is secreted by the anterior pituitary and binds to a plasma protein.
Explanation:
Growth hormone (GH) exerts many of its effects on growth and metabolism by stimulating the production and release of polypeptide growth factors called somatomedins from the liver, cartilage, and other tissues. In humans, the principal circu- lating somatomedins are insulin-like growth factor I (IGF-I, somatomedin C) and IGF-II. GH release is stimulated by growth hormone-releasing hor- mone (GHRH) and ghrelin and inhibited by somatostatin. All of these pep- tides are synthesized and released by the hypothalamus, though the main site of ghrelin synthesis and secretion is the stomach. GH increases lipoly- sis; the resultant increase in free fatty acids, which takes several hours to develop, provides a ready source of energy for the tissues during hypo- glycemia, fasting, and stressful stimuli. GH also has a protein anabolic effect. GH is metabolized rapidly; the half-life of circulating GH in humans is 6 to 20 minutes
