Natri là các cation có nhiều nhất trong dịch ngoại bào và là yếu tố quan trọng trong osmolality ngoại bào (nồng độ của các hạt hòa tan trong máu). Sodium thường di chuyển bằng nước và chuyển nước với natri, do đó, như là một yếu tố quyết định của osmolality, nồng độ của natri có tác động đến dòng chảy của nước qua màng tế bào. | 80 Fluids and Electrolytes Demystified 5 Discuss the potential complications related to hyponatremia and hypernatremia. 6 Determine the nursing implications related to treatments for sodium imbalances. Key Terms Aldosterone Diuresis Edema Hypernatremia Osmolality Polyruria Hyponatremia Overview Sodium is the most abundant cation in the extracellular fluid and is the major factor in extracellular osmolality the concentration of particles dissolved in blood . Sodium commonly moves with water and water moves with sodium thus as a determinant of osmolality the concentration of sodium has an impact on the flow of water across the cell membrane. Additionally the concentration of sodium and volume of water play a critical role in blood pressure. Sodium also plays an important role in nerve impulse generation and transmission. As a part of the sodium-potassium pump the difference between the potassium and sodium concentrations is maintained through active transport across the cell membrane as needed with the help of adenosine triphosphate ATP as an energy source. The flow of sodium and potassium across the cell membrane of electrically charged cells results in depolarization. Thus sodium is important for nerve and muscle function. As such sodium imbalances can affect cardiac and respiratory muscle function as well as mobility. Sodium also plays a role in acid-base balance. Sodium binds well to chloride and bicarbonate and thus plays a part in the metabolic buffer system preventing a strong acid from greatly affecting the pH of the blood by changing it to a weak acid. HCl NaH2CO3 NaCl H2CO3 strong acid strong base salt weak acid Thus sodium plays an important role in fluid balance neuromuscular function and acid-base balance. Excessive or inadequate concentrations of sodium can severely disrupt body function. CHAPTER 5 Sodium Imbalances 81 Sodium is absorbed in the intestines from foods and fluids ingested as well as from many medications. The intake of sodium commonly far
