1 The phenotype may change constantly throughout the life of an individual because of environmental changes and the physiological and morphological changes associated with aging.
One special group of hormones is the tropic hormones that stimulate the hormone production of other endocrine glands. For example, thyroid-stimulating hormone (TSH) causes growth and increased activity of another endocrine gland, the thyroid, which increases output of thyroid hormones. hormone (from Greek á½ÏÎ¼Î®, impetus) is any member of a class of signaling molecules produced by glands in multicellular organisms that are transported by the circulatory system to target distant organs to regulate physiology and behaviour.
Growth hormone (GH) indirectly (through insulin-like growth factors, IGFs) stimulates body cells to increase in size and divide. Direct effects are insulin-sparing: mobilization of fatty acids for fuel, inhibition of insulin activity, release of glucose from liver to blood, and stimulation of amino acid uptake by cells. GHRH, secreted from the hypothalamus, is the stimulus for GH release.