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IV - Balance A Importance of Ca 1 bone is...

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Fluid, Electrolyte, Acid/Base Balance IV. Regulation of Potassium (K + ) Balance A. Importance of K + 1. K + is primary CATION ( + ) within cells 2. K + abnormalities cause changes in Resting Mem Pot (neurons, cardiac muscle especially) B. Renal Control of K + Levels 1. 10-15% constantly lost in urine 2. most resorption occurs in Proximal Tubule 3. regulation - changing amount SECRETED into urine in the collecting tubules a. low K + ----> less secretion (intercalated cells in collecting tube can reabsorb more) b. high K + -----> more secretion C. Factors Controlling K + Secretion 1. tubule cell intracellular K + level - when low, secrete less; when high, secrete more 2. aldosterone level - K + secreted: Na + reabsorbed a. increase aldosterone -> more K + secretion b. decrease aldosterone -> less K + secretion 3. pH - K + and H + compete for antiport with Na + a. lower pH (high H + ) -> less K + secretion b. higher pH (low H + ) -> more K + secretion V. Regulation of Calcium (Ca
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Unformatted text preview: ++ ) Balance A. Importance of Ca ++ 1. bone is the "reservoir" of most Ca ++ in the form of Calcium Phosphate (Ca ++ with PO 4-2 ) 2. primary physiological roles (already covered): a. at the muscle and neuron synapse b. essential for blood clotting process c. very critical in heart rhythms B. Ca ++ Regulation: Parathyroid Hormone (PTH) & Calcitonin 1. parathyroid hormone (PTH) - chief control when Ca ++ begins to DECREASE too low a. bones - Ca ++ and PO 4-2 release to blood b. small intestine - activates Vitamin D which is essential for Ca ++ resorption c. kidneys - Ca ++ reabsorbed (but PO 4-2 excreted) Fluid, Electrolyte, Acid/Base Balance 2. calcitonin (thyroid gland) - released when Ca ++ begins to INCREASE too high a. inhibits Ca ++ release from bone, increases actual formation of Calcium Phosphate in bone...
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