Growth hormone: Difference between revisions
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Growth hormone is an important regulator of growth and cell reproduction and a deficiency in this hormone gives rise to growth failure, reduced muscle and bone mass and many other problems relating to development of the body. In extreme cases, pituitary dwarfism can occur. Too much growth hormone can result in a pituitary tumour which causes gigantism if the tumour occurs during childhood. | Growth hormone is an important regulator of growth and [[cell|cell]] reproduction and a deficiency in this [[hormone|hormone]] gives rise to growth failure, reduced [[muscle|muscle]] and [[bone|bone]] mass and many other problems relating to development of the body. In extreme cases, [[Pituitary_gland|pituitary]] dwarfism can occur. Too much growth hormone can result in a pituitary tumour which causes gigantism if the tumour occurs during childhood. | ||
Growth hormone is synthesised by somatotroph cells of the anterior pituitary gland and its synthesis is stimulated by the binding of growth hormone-releasing hormone to the GHRH receptor.This receptor is G protein-coupled receptor, so when GHRH binds, | Growth hormone is synthesised by somatotroph cells of the [[Anterior_pituitary_gland|anterior pituitary gland]] and its synthesis is stimulated by the binding of growth hormone-releasing hormone to the [[GHRH receptor|GHRH receptor]]. This receptor is [[GPCR|G protein-coupled receptor]], so when GHRH binds, [[Adenylyl_cyclase|adenlyly cyclase]] is activated which increase intracellular levels of [[cAMP|cAMP]]. As a result, [[gene |gene]] transcription is stimulated and growth hormone is synthesised. The release of stored GH is also activated via the G protein messenger pathway as increased levels of cAMP opens [[calcium channel|calcium channels]] causing intracellular [[calcium|calcium]] levels to rise. When this happens, the release of growth hormone from the [[samatotroph cells|samatotroph cells]] is stimulated.The growth hormone-releasing hormone is released from the [[hypothalamus|hypothalamus]] when its nuclei are stimulated by [[neuron|neurones]] in response to factors such as sleep, fasting, puberty and strenuous exercise. | ||
The growth hormone itself is a 191 amino acid long polypeptide encoded by a gene on the long arm of chromosome 17 with a weight of 22- | The growth hormone itself is a 191 [[amino acid|amino acid]] long [[polypeptide|polypeptide]] encoded by a [[gene|gene]] on the long arm of [[chromosome 17|chromosome 17]] with a weight of 22 kDa <ref>Walter F. Boron, 2009. Medical physiology. 2nd ed. Philadelphia. Saunders Elsevier</ref><ref>Tanner JM. 1972. Human Growth Hormone. Nature. (5356), pp.433-9.</ref>. <br> | ||
<br> | === References<br> === | ||
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Latest revision as of 06:23, 26 October 2012
Growth hormone is an important regulator of growth and cell reproduction and a deficiency in this hormone gives rise to growth failure, reduced muscle and bone mass and many other problems relating to development of the body. In extreme cases, pituitary dwarfism can occur. Too much growth hormone can result in a pituitary tumour which causes gigantism if the tumour occurs during childhood.
Growth hormone is synthesised by somatotroph cells of the anterior pituitary gland and its synthesis is stimulated by the binding of growth hormone-releasing hormone to the GHRH receptor. This receptor is G protein-coupled receptor, so when GHRH binds, adenlyly cyclase is activated which increase intracellular levels of cAMP. As a result, gene transcription is stimulated and growth hormone is synthesised. The release of stored GH is also activated via the G protein messenger pathway as increased levels of cAMP opens calcium channels causing intracellular calcium levels to rise. When this happens, the release of growth hormone from the samatotroph cells is stimulated.The growth hormone-releasing hormone is released from the hypothalamus when its nuclei are stimulated by neurones in response to factors such as sleep, fasting, puberty and strenuous exercise.
The growth hormone itself is a 191 amino acid long polypeptide encoded by a gene on the long arm of chromosome 17 with a weight of 22 kDa [1][2].