ADH acts on ?

Ans. is `c' i.e., Collecting ductAntidiuretic hormone (ADH) ADH (vasopressin) is a nonapeptide secreted by posterior pitutary (neurohypophysis) along with oxytocin.It is synthesized in hypothalamus (Supraoptic and paraventricular area) nerve cell bodies as large precursor peptide along with its binding protein neurophysin and is transpoed down the axons to nerve endings in the median eminence and pars nervosa.The two main physiological stimuli for ADH release are rise in plasma osmolarity and contraction of ECF volume.Other factors which can influence ADH secretion are:Inhibit ADH secretion: Cold environemnt, ethyl alcoholStimulate ADH secretion: Pain, exercise, stress, sleep and drugs like morphine