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21 Cards in this Set
- Front
- Back
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What is neurosecretion?
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capacity of a nerve cell to secrete a hormone
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What are the three stages of the hypothalamo-pituitary system?
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1)hypothalamic nuclei
2) hypothalamo-neurohypophyseal tract/infindibulum 3) posterior pituitary gland |
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What are the two nuclei of the hypothalamus that regulate the hypothalamo-neurohypophyseal system?
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1) supraoptic nucleus
2) paraventricular nucleus |
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What happens to the hormones in each of the different places? (5 steps)
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1) hormones made in supraoptic and paraventricular nuclei
2) processing of pre-prohormone to release prohormone 3) prohormones packaged in granules 4) postribosomal proteolytic processing to get hormones in infindibulum 5) storage and release of hormones in neurohypothesis via excitation-secretion coupling |
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What are the elements of the hypothalamo-adenohypophyseal system? (2)
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1) hypothalamo-hypophyseal portal system transport releasing and inhibiting hormones from hypothalamus to median eminence of hypothalamus
2) from there they go to anterior pituitary via portal venous system |
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How do vasopressin and oxytocin get transported into blood?
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soluble
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What is the underlying mechanism of vasopressin/ADH action?
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1)V1 receptor: contraction of vascular smooth muscle (vasopressor)
2) V2 receptor: increase water resorption in DCT |
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What mechanism does the V1 receptor use?
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Ca--> PLC--> IP3 +DAG
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What mechanism does the V2 receptor use?
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cAMP-->PKA--> CREB-->CRE --> xcription of water channels aqapourins
phosphorylation of aquaporins insertion of aquaporins into cell membrane |
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What are the major signals of vasopressin secretion?(8)
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1) hypovolemia
2) hyperosmolarity 3) stress/anxiety/pain 4)nicotine 5) opiates/barbituarates 6) β adrenergic agonists 7) estrogens 8) increased pCO2, decreased pO2 |
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What is the most potent stimuli for ADH secretion?
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hypovolemia
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What is the mechanism for hypovolemia and ADH secretion? (3)
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1)increased stretch in left atria receptors
2)increased firing of vagal inhibtory signals 3)decreased vasopressin release |
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What is the mechanism for hyperosmolarity?
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hypothalamic osmoreceptors near magnocellular nuclei
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What are the two disorders of vasopressin secretion?
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1) Diabetes Insipidus
2) Syndrome of Innapropriate Antidiuretic Hormone (<b>SIADH</b>) |
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What is the cause of diabetes insipidus?
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decreased ADH secretion
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What is the cause of SIADH
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increased ADH due to increased sensitivity of osmoreceptors
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What are the symptoms of SIADH?
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1) ECF expansion
2) serum hypotonicity 3) serum hyponatremia |
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What are the symptoms of diabetes insipidus?
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1) polyuria
2) polydipsia |
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What are the three mechanisms of diabetes insipidus?
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1) neurogenic - absence of vasopressin
2) nephrogenic- unresponsiveness to ADH in target cells of nephron 3) pregnancy |
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What are the functions of oxytocin in female?
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contraction of myoepithelial cells as in
1)partuition 2) milk ejection 3) sperm transport |
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What are the functions of oxytocin in males?
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oxytocin release occurs during ejaculation
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