45 out of 95
All of the following statements are correct about potassium balance. Except:
|A||Most of potassium is intracellular|
|B||Three quarter of the total body potassium is found in skeletal muscle|
|C||Intracellular potassium is released into extra-cellular space in response to severe injury|
|D||Acidosis leads to movement of potassium from extracellular to intracellular fluid compartment.|
Ans. D Acidosis leads to movement of potassium from extracellular to intracellular fluid compartment.
- Potassium is the major intracellular cation. Q The normal plasma concn of K+ is in 3.5 to 5.0 mmol/L, where as that inside cells is about 150 m mol/L.
- Tissue destruction or breakdown results in release of the intracellular K+ [leading to hyperkalemia] where as the production of new cell shift K+ out of ECF. Finally modulate to severe exercise may be associated with K+ release from muscle, leading to glycogenolysis and local vasodilation.
- The role of extracellular pH in K+ balance relates to the underlying acid base disorder. In metabolic acidosis 60% of the H+ load is buffered inside cells. To maintain electroneutrality, the H+ ion must either be accompanied by an anion or exchanged for intracellular K+ (leading to hyperkalemia).
- CMDT 2001, page 877 also writes, that intracellular potassium shifts to the extracellular fluid in hyperkalemia associated with acidosis. Serum K+ concn rises about 0.7 meq/L for every decrease of 0.1 pH unit during acidosis. Q
- Organic acidosis are not usually associated with a pH - related K+ shift, since anions such as lactate and -hydroxybutyrate can be readily taken up by the cells Q The converse movement of K+ into cells, may be seen with metabolic alkalosis [i.e. that from extracelluar to intracellular fluid compartment as in option 4].