Enzyme linked immunosorbent assay (elisa) 1.elisa can be used to measurd almost any protein, including hormones. 2. it is often performed on plastic plates that each have 96 small wealls. 3. each well is coated with an antibody that is specific for the hormone being assayed . 4. samples or standards are added to each of the wells , followdd by asecond antibodz that is also specific for the hormone bu binds to a different site of the hormone molecue. 5. a third antibody is added that recognizes and is coupled to an enzyme that converts a suitable substrate to a product that can be easily detected by colorimetric or fluorescent optical mdthod. 6. because each molecule of enzyme catayzes the formation of many thousands of product molecules, even very small amounts of hormone molecules be detected. hormone secretion : negative feedback prevents overactivity of hormone systems. 1.after a stimulus causes release of the hormone conditions or products resulting from the action of the hormone tend to suppress its further release. 2. the controlled variable is often not the secretory rate of the hormone itself . 3.when the target tissue activity rises the endocrine gland become powerful enough to sjow further secretion of the hormone. 4. it occurs all levelr. surges of hormones can occur with positive : 1. when additional secretion of the hormond. 2. the surge of luteinizing hormone that occurs as a result of the stimulatory effect. 3. the secreted lh then acts on tqe ovaries to stimulate additional secretion of estrogen. cyclical variations occur in hormone release. hormone release are influenced by seasonal changes, various stage of devdlopment and aging the diurnal cycle and sleep.
Posted on: Tue, 18 Jun 2013 05:08:46 +0000
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