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Decrease.Hormone regulationJuly 2018
BIOS256 Midterm Study GuideTYPE OF REGULATIONMAJOR STIMULUSMECHANISM AND SITE OF ACTIONEFFECT ON GFRAngiotensin IIDecreased blood volume or blood pressure stimulates production of angiotensin II.Constriction of afferent and efferentarterioles.Decrease.Atrial natriuretic peptide (ANP)Stretching of atria of heart stimulates secretion of ANP.Relaxation of mesangial cells in glomerulus increases capillary surface area available for filtration.Increase.(Ch. 26) Tubular reabsorption and secretion(Ch. 26) Table 26.4HORMONEMAJOR STIMULI THATTRIGGER RELEASEMECHANISM AND SITE OF ACTIONEFFECTSAngiotensin IILow blood volume or low blood pressure stimulatesrenin-induced production of angiotensin II.Stimulates activity of Na+–H+antiporters in proximal tubule cells.Increases reabsorption of Na+, other solutes, and water, which increases blood volume and blood pressure.AldosteroneIncreased angiotensin II level and increased level of plasma K+promote release of aldosterone by adrenal cortex.Enhances activity of sodium–potassium pumps in basolateral membrane and Na+channels in apical membrane of principal cells in collecting duct.Increases secretion of K+and reabsorption of Na+, Cl−; increases reabsorption of water, which increases blood volume and blood pressure.Antidiuretic hormone (ADH)Increased osmolarity of extracellular fluid or decreased blood volume promotes release of ADH from posterior pituitary gland.Stimulates insertion of water channel proteins (aquaporin-2) into apical membranes of principal cells.Increases facultative reabsorption of water, which decreases osmolarity of body fluids.Atrial natriuretic peptide (ANP)Stretching of atria of heart stimulates ANP secretion.Suppresses reabsorption of Na+and water in proximal tubule and collecting duct; inhibits secretion of aldosterone and ADH.Increases excretion of Na+in urine (natriuresis); increases urine output (diuresis) and thus decreases blood volume and blood pressure.Parathyroid hormone (PTH)Decreased level of plasma Ca2+promotes release of PTH from parathyroid glands.Stimulates opening of Ca2+channels in apical membranes of early distal tubule cells.Increases reabsorption of Ca2+.(Ch. 26) Formation of concentrated urine(Ch. 26) Evaluation of kidney functionShort Answer Questions