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Antidiuretic hormone (vasopressin) A. Is released from nerve endings in the posterior pituitary gland. B. Tends to raise the osmolality of plasma rise. C. Increases the permeability of the cells in the loop of Henle to water. D. Secretion is little affected by changes in plasma osmolality of less than 10 per cent. E. Secretion increases when plasma volume falls but osmolality is unchanged. |
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Answer» A. True It is formed in neurones whose cell bodies lie in the hypothalamus and whose axons transport it to the posterior pituitary gland. B. False The water retention it induces makes plasma osmolality fall. C. False It increases the permeability of the collecting ducts. D. False Secretion is affected by 1 per cent changes in osmolality; the sensitivity of the hypothalamic receptors to osmolar change accounts for the constancy of plasma osmolality. E. True Volume changes detected by vascular low-pressure receptors affect ADH secretion. |
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