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.
This signal is called thyroid stimulating hormone (TSH). As the name implies, this hormone stimulates the thyroid to produce thyroid hormone and to grow in size. This abnormal growth in size produces what is termed a âgoiter.â Thus, iodine deficiency is one cause of goiter development. Wherever iodine deficiency is common, goiter will be common.