L12- DI - Diabetes Insipidus & ADH...

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Unformatted text preview: Diabetes Insipidus & ADH hypersecretion Dr. Abdulmoein Eid Al-Agha Assistant Professor & Consultant Pediatric Endocrinologist, King AbdulAziz University & Dr. Erfan Hospital - Jeddah The Pituitary Gland The pituitary composed of 2 lobes: anterior lobe adenohypophysis posterior lobe neurohypophysis Posterior Pituitary: Hormones synthesized in the hypothalamus are transported down the axons to the endings in the posterior pituitary Hormones are stored in vesicles in the posterior pituitary until release into the circulation Principal Hormones: Vasopressin & Oxytocin Posterior Pituitary Hormones Antidiuretic Hormone (ADH) ADH is a polypeptide hormone, synthesized in the supraoptic & paraventricular nuclei in the hypothalamus &is released in response to a number of stimuli ADH is rapidly metabolized in the liver and kidneys and has a half-life of 15-20 minutes The primary effect of ADH is to increase water retention by the kidney The result of this is to decrease urine volume and increase the volume of extracellular fluid Hypothalamic regulation of the Posterior pituitary lobe The posterior pituitary secretes oxytocin & (ADH), both are synthesized in the supraoptic & para- ventricular nuclei of the hypothalamus They are transported to the posterior pituitary through axons of the same neurons that produced them Posterior Pituitary: Regulation of Osmolality Plasma Osmolality is monitored by osmoreceptor in the hypothalamus Increases in plasma Osmolality stimulates secretion of vasopressin Small changes above the normal plasma osmotic pressure (285 mosm/kg) stimulate release of vasopressin ADH is released by the posterior pituitary when water deprivation causes increased plasma Osmolality the cardiovascular system is challenged by hypovolemia and/or hypotension Functions: increases the passive water permeability of the cell membrane of the nephron collecting ducts Is a potent vasoconstrictor is a neurotransmitter in CNS regulation of the secretion of ACTH the cardiovascular system, temperature and other visceral functions. Promotes hemostasis the release of endothelial coagulation factors. increases platelet aggregability Water regulation 1) Osmoreceptors are neurons in the CNS 2) Baroreceptors in left atrium, left ventricle, and pulmonary veins sense blood volume (filling pressures), and baroreceptors in the carotid sinus and aorta monitor arterial blood pressure What are the differences between the V1 &...
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This note was uploaded on 12/21/2011 for the course STEP 1 taught by Professor Dr.aslam during the Fall '11 term at Montgomery College.

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L12- DI - Diabetes Insipidus & ADH...

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