ADH and the arterioles, kidneys, sweat glands and the Atrial natriuretic peptide (ANP)

• ADH is also known as vasopressin. • Produced by hypothalmus and secreted by neurosecretory cells in posterior pituitary gland. • Responds to high blood osmotic pressure representing low amounts of water in the blood. • Binds to smooth muscle cells in walls of arterioles, stimulates vasoconstriction. • Increases SVR and raises MABP back toward normal. ■ ADH binds to principal cells forming the walls of nephron tubules in kidney. ■ Stimulates tubules to add water pores (aquaporins) to surface membranes, increasing permeability of tubules to water. ■ Increased permeability increases reabsorption of water and blood volume. • Increased CO raises MASP back toward normal. • Water retention also returns blood osmotic pressure to normal. ■ ADH binds to the sweat glands, inhibiting sweating. • Greater water retention increases blood volume and helps normalize blood osmotic pressure. • Increased CO raises MABP back toward normal. • Secreted when increased blood volume stretches cells in the atria of the heart. • Lowers MABP via vasodilation, sodium and water excretion, and reduced blood volume. • Targets cells of proximal convoluted tubule in kidney. • Increases urine production by inhibiting retention of Na+ ions and water. • Less water retention lowers blood volume and returns MABP toward normal.

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