PHGY 210 Lecture Notes - Lecture 5: Extracellular Fluid, Fluid Compartments, Carambola
27 Nov 2015
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Renal physiology lecture 5: potassium and hydrogen ion regulation. Potassium (k) is the most abundant intracellular ion: 98% intracellular fluid, 2% extracellular fluid. The k concentration in the extracellular fluid is extremely important for the function of excitable tissues (nerve and muscle) Reason: the resting membrane potentials of these tissues are directly related to the relative intracellular and extracellular k concentrations. Hyperkalemia: high concentration of k in the extracellular fluid (>5 meq/l) Hypokalemia: low concentration of k in the extracellular fluid (<3. 5 meq/l) Both cause abnormal rhythms of the heart and abnormalities of skeletal muscle contraction. Effect of hyperkalemia on the electrocardiogram - pre cardiac arrest. From the dietary intake, 90% is excreted into urine and 10% is excreted into feces/sweat. Bananas, papaya, pineapple, starfruit, watermelon, are rich sources of potassium. Normally, the tubules reabsorb most of this filtered k so that very little of the filtered k appear in the urine.
