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Organic nutrients (glucose, amino acids) all reabsorbedWater, ions continuously regulated
Methods of ReabsorptionActive Transport: ATP used to move molecules across membrane.SodiumSecondary Active Transport: when Active Transport of one molecule helps to move another molecule across a membrane (via a co-transporter).Glucose, amino acids, vitaminsPassive Transport: a concentration gradient drives diffusion of a molecule across a membrane.Water, ions
Passive Transport of Water Obligatory water reabsorptionFacultative water reabsorptionWater reabsorbed regardlessof state of over- or under-hydration of bodyLocation: PCT, nephron loop (descending limb)Water reabsorption that depends on ADH (hormone-controlled)Location: Collecting duct
Hormonal Regulation of Tubular ReabsorptionReabsorption of water and solutes only controlled in DCT and Collecting Duct.HormoneFunctionAntidiuretic Hormone (ADH)During dehydration, ADH increases -> decreases urine output by causing more reabsorption of water in CD (opposite in over-hydration)AldosteroneIncreases Na+reabsorption in DCT & CDGoal is to increase blood volume and pressureAtrial Natiuretic Peptide (ANP)Decreases Na+reabsorption in CDOpposite to AldosteroneParathyroid Hormone (PTH)Increases reabsorption of Ca2+in DCT