Aden late cycles is activated D camp accumulates intracellular the camp, ultimately speaking

acts on the cytoskeleton of these cells (for details of cytoskeleton, see chap I sec I) ultimately this causes development of fine intra cellular channels within the cells communicating with the extensor (the tubular lumen) through which water passes for reassertion Control of ADH secretion there are Iowa major means by which the body controls the ADH secretion as described below 1 Amorality of blood Whittle body develops water deprivation (e g . no drinking water for long Time) the osmotic tension of the blood becomes higher than normal, the hypertonic blood stimulates the osmoreceptyors present in the hypothalamus the osmoreceptors now send nerve impulses to the (supraoptic nuclei of the) hypothalamus and the hypothec amuse secretes the ADH the concept of osmoreceptors was first developed by E D Emery of England in the 1940s Subsequently, Verne showed that these oamoreceptois are situated in the regions of supraoptic and par a ventricular nuclei of the hypothalamus Normal values osmolafty of plasma is about 290 m ormolus/kg. Only a slight rise of the amorality from this value triggers off the mechanism to stimulate the secretion of ADH This means as the body is dehydrated even slightly, the osmotic tension of plasma becomes higher, the osmoreceptore then are stimulated D ADH secretion Occurs water loss through the kidney is reduced, i e . body water conserved disturbances in water homeostasis is checked. If there is hypervolemia of the blood, ADH secretion is slopped Mechanism is as follows . the hypervolemia causes distension in the. atnum. the stretch receptors in the atria wall are stimulated and the afferent impulses from these stretch receptors reach the hypo helium* and ADH secretion is stopped This means, during hypervolemia (say due to excess saline transfusion), there is stoppage of ADH dilute and large volume urine is passed correction of hypervolemia Fig6.5.4 Control oath Many other factors can stimulate and inhibit ADH secretion Some such factors are diagrammatically sum married in fig6.5.4 it should be understood, a vary large number of drugs can influence ADH secretion, although they have not been shown in fig 6. 5. 4. Oxytocin its chemistry and biosynthesis