R7 Role of Antidiuretic hormone (ADH) in urine concentration and volume and Diruetics

ADH, also known as vasopressin, is produced in the hypothalamus and delivered to the posterior pituitary for storage and release

the most important effect of ADH is to conserve body water by reducing the loss of water in urine

it stimulates water reabsorbtion by stimulating insertion of aquaporins into the luminal membrane of principal cells of the collecting duct

it works via the cAMP pathway

it is secreted in response to increasing osmolarity in the blood

this is sensed by osmoreceptors in the hypothalamus which stimulate the posterior pituitary into releasing ADH

absence of ADH results in large amount of dilute urine produced (or diabetes insipidus)

ADH secretion is also stimulated by angiotensin II

Diuretics

A diuretic is an agent that increases urine output and therefore decreases water conservation by the body.

they increase urine output via different mechanisms

an osmotic diuretic is a substance that is not reabsorbed and that carries water out with it

eg high blood glucose of a diabetes mellitus

patient

alcohol acts by inhibiting ADH secretion

xanthines such as caffeine and theophylline act by inhibiting Na+ reabsorption and the

obligatory water reabsorption that normally

follows

lasix inhibits the Na+-K+-2Cl- cotransporter in the medullary thick ascending limb of the loop of Henle

diuretics are used to treat hypertension, congestive heart failure, and fluid retention associated with menstruation