Biology Is Love

  Why Oxytocin and Vasopressin called as 'neuro hormone'?      -souti das                            The posterior pitutary secretes two hormone oxytocin and vasopressin(ADH).The hormones are synthesized within the cell bodies of large magnocellular neurons lying in the supraoptic and paraventricular nuclei (PVN) of the hypothalamus.                            The posterior pituitary hormones are transported in association with specific proteins, called neurophysins , along the axons of the neurons to end in those nerve terminals which lie within the posterior lobe. Prior to secretion, these hormones are stored in secretory granules either in the nerve terminals or in the varicosites called herring bodies . The hormones are secreted in response to nerve impulses originating in the supraoptic and PVN and enter the capill...

  Time Dependent Potentiation of Insulin secretion   Glucose causes time dependent potentiation(TDP) of insulin secretion; that is exposure of islets beta cells to high glucose enhances insulin release in response to the stimulus applied later.

Wolf-Chaikoff Effect It is a reduction in thyroid hormone levels caused by ingestion of a large amount of iodine(more than 2mg/day) which suppresses NADPH oxidase activity as well as NIS & TPO genes expression. Jan Wolff and Isreal Lyon Chaikoff first reported that injection of iodine in rats almost completely inhibited " Organification of iodine " in the thyroid gland by an " Autoregulatory phenomenon ".  The Wolff-Chaikoff effect lasts several days(~10 days), after which it is disappeared by a process known as " Escape Phenomenon " which is described by resumption of normal organification of iodine and normal TPO function.                     The Wolff-Chaikoff effect can be used as a treatment principle against hyperthyroidism by infusion of a large amount of iodine to suppress the thyroi d gland.  By- Souti Das image source- twitter