Growth Regulation Hormone Assignment Example | Topics and Well Written Essays - 3000 words

Growth Regulation Hormone - Assignment Example The specific receptor of GH (GHR) is a 638-aminoacid protein, a receptor of the extrinsic tyrosine kinase group encoded on chromosome 5. It consists of an extracellular part to bind GH, a trans-membrane sequence and a cytoplasmic part. The GHR-JAK2(Janus tyrosine kinase) activation of signalling molecules can result in different cellular responses, some of which involve the activation of transcription from target genes, while others involve metabolic changes. Introduction Growth Regulatory Hormones are those hormones secreted under the control of the endocrine system. They include the Growth Hormone, somatostatins, somatomedins (IGFs) and others which are important in regulating the various aspects of growth in the body. The most important of these is the Growth Hormone (GH) which will be studied in details in this review. It is secreted from the anterior pituitary under the command of Growth Hormone Releasing Hormone of the hypothalamus and is regulated and modulated by various othe r hormones and exert its growth promoting actions by activating various signalling pathways and cross talk mechanisms which will be elucidated in this review. In this review we will specifically focus on GH and its relation to other hormones and molecular mechanisms regulating growth in the body.[1,2,3,] Growth Regulatory Hormones: A Preview Regulation of body growth is under the control of the endocrine system, which is a coordinated system of hormones secreted by special glands in the body. These hormones regulate every aspect of growth, metabolism and sexual functions also. The chief hormones regulating body growth are: Growth hormone (GH) GH, also called the somatotrophic hormone is the key regulator of growth in the body. They increase the synthesis of various proteins and elongate the bones at the growth plates. In childhood and adolescence it causes increase in height. There are other roles also like increasing the muscle mass, calcium retention in the bones and stimulating t he immune system. Growth Hormone Releasing Hormone (GHRH) The endocrine system is finely regulated for secretion of various hormones by feedback mechanisms. Thus GHRH is secreted from the hypothalamus controls the secretion of GH secretion from the pituitary gland.This means when GH pulse is low, increased GHRH secretion cause pineal gland to revive the pulse of GH and when GH pulse is high GHRH secretion decreases. Somatostatin Also called the Growth Hormone Inhibiting Hormone (GHIH) it decreases the amount of GH in the body. It is also secreted from the hypothalamus and tightly controls the release of GH in association with GHRH. Estrogen and Progesterone These hormones start the growth spurt seen in at the beginning of puberty by activating GH. They also functions to seal off the growth plates when a person reaches his adult height. These hormones start the growth spurt seen in at the beginning of puberty by activating growth hormone. They also function to seal off the growth pla tes when a person reaches his adult height. [1,2,3,4] Background of Growth Hormone Secretion Growth Hormone is secreted in a pulsatile manner from the anterior pituitary gland. It is a peptide hormone consisting of 191 amino acid residues and contains 2disulphide bonds. The 20kda and 22kda isoforms are the important ones. There are 5