Posterior Pituitary Hormones

Posterior Pituitary - The 2 Posterior Pituitary Hormones ADH and Oxytocin Antidiuretic hormone(ADH and Oxytocin are synthesized by the hypothalamus

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The 2 Posterior Pituitary Hormones – ADH and Oxytocin Antidiuretic hormone (ADH) and Oxytocin are synthesized by the hypothalamus Transported via the hypothalamic-hypophyseal tract to the posterior pituitary ADH and Oxytocin are stored/released from the posterior pituitary. Both ADH and Oxytocin are nonapeptide – each composed of 9 amino acids
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Figure 16.1 The Major Endocrine Glands
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Pituitary Gland
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Figure 16.6
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Antidiuretic Hormone (ADH) = Arginine Vasopressin (AVP) Major STIMULI for the release of ADH : Dehydration Hemorrhaging Hypovolemia (refer to next slide) Hypotension – decreased blood pressure Hyperosmolality of blood - Increased blood osmolality (refer to next slide) Estrogens ( this explains the water retention/bloating associated with the menstrual cycle) Major Biological Actions of ADH : ADH binds to cell surface receptors called V1 and V2 receptors ADH binds to V2 receptors to induce the cAMP signal transduction mechanism ADH binds V1 receptors to induce the PIP/IP3 signal transduction mechanism . 1. ADH binds to V2 receptors on collecting ducts in the kidneys to stimulate water reabsorption (the collecting ducts are impermeable in the absence of ADH) increasing the blood volume and decreasing urine volume (its antidiuretic effect) ADH stimulate the translocation of aqueous cannels called aquaporins to insert at the plasma membrane of the cells in the collecting duct to allow water reabsorption – this type of water absorption is referred to as FACULTATIVE WATER REABSORPTION 2. ADH binds to V1 receptors on the smooth muscle cells in the wall of the blood vessels to cause vasoconstriction increases the TPR increases blood pressure ( its vasopressive
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This document was uploaded on 10/27/2011 for the course BSCI 447 at Maryland.

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Posterior Pituitary - The 2 Posterior Pituitary Hormones ADH and Oxytocin Antidiuretic hormone(ADH and Oxytocin are synthesized by the hypothalamus

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