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Physiology

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Basic Concepts

Question
34 out of 95
 

Sodium-potassium-ATPase helps in the mainte-nance of which of the following?



A Cell surface charge

B Cell volume

C Low extracellular sodium

D High extracellular potassium

Ans. B >A

  1. The sodium-potassium pump is the most commonly active transport mechanism in the body.
  2. This pump is present in all cells in body and is responsible for maintaining the sodium and potassium concentration differences across the cell membrane as well as for establishing a negative electrical potential inside the cells.
  3. When 3 sodium ions bind on the inside of this carrier protein and 2 potassium ions on the outside, the ATPase function of the protein becomes activated Q.
  4. This then cleaves 1 molecule of ATP, splitting it to ADP and liberating a high-energy phosphate bond of energy.
  5. This energy is then believed to cause a conformational change in the protein carrier molecule, extruding the sodium ions to the outside and the potassium ions to the inside.
  6. By this process a net of 1 positive charge is moved from the interior of the cell to the exterior for each revolution of the pump.
  7. This creates positivity outside the cell but leaves a deficit of positive ions inside the cell; that is, it causes negativity on the inside.
  8. Therefore, the sodium-potassium pump is said to be electrogenic Q because it creates an electrical potential across the cell membrane as it pumps.
  9. One of the most important functions of the sodium-potassium pump is to control the volume of the cells. Without function of this pump, most cells of the body would swell until they burst Q.

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