Final answer:
The concentration of sodium in the blood plasma is approximately 150 mEq/L, which is essential for maintaining osmotic balance and regulated mainly by the kidneys.
Step-by-step explanation:
The composition of sodium in the blood plasma is equal to approximately 150 mEq/L. This is because one milliequivalent (mEq) of sodium (Na+), which has a 1+ charge, is equal to one millimole (mmol). Taking into account that an intravenous saline solution contains 145 mEq/L of Na+, it is close to the sodium concentration in human blood plasma.
Furthermore, in terms of osmolarity, body fluids are maintained within the range of 280 to 300 mOsm, and sodium is the major cation of the extracellular fluid, contributing significantly to this measure. Sodium levels in blood plasma play a crucial role in maintaining proper osmotic balance and blood pressure, and the kidneys primarily regulate this concentration.