What is the normal range of serum sodium in adults?

Choice A reason: Intracellular to the extracellular fluid shift is not the cause of low blood pressure in this case. This fluid shift occurs when the cells lose water due to osmosis, such as in dehydration or hypernatremia.

Choice B reason: Interstitial to intravascular fluid shift is not the cause of low blood pressure in this case. This fluid shift occurs when the fluid moves from the tissue spaces to the blood vessels, such as in hypovolemia or hypotonic fluid administration.

Choice C reason: Interstitial to the intracellular fluid shift is not the cause of low blood pressure in this case. This fluid shift occurs when the fluid moves from the tissue spaces to the cells, such as in overhydration or hyponatremia.

Choice D reason: Intravascular to the interstitial fluid shift is the cause of low blood pressure in this case. This fluid shift occurs when the fluid moves from the blood vessels to the tissue spaces, such as in edema, inflammation, or increased capillary permeability. This reduces the blood volume and lowers the blood pressure.

Choice A reason: This is incorrect because intracellular fluid is greater than extracellular fluid in a hypertonic state, not an isotonic state. A hypertonic state is when the solute concentration of the extracellular fluid is higher than the intracellular fluid, which causes water to move out of the cells and shrink them.

Choice B reason: This is incorrect because extracellular fluid is less than intracellular fluid in a hypotonic state, not an isotonic state. A hypotonic state is when the solute concentration of the extracellular fluid is lower than the intracellular fluid, which causes water to move into the cells and swell them.

Choice C reason: This is correct because intracellular and extracellular fluid is equal in an isotonic state. An isotonic state is when the solute concentration of the extracellular fluid is the same as the intracellular fluid, which causes no net movement of water across the cell membrane.

Choice D reason: This is incorrect because interstitial fluid is less than the transcellular fluid in a situation of fluid imbalance, not an isotonic state. Interstitial fluid is the fluid that surrounds the cells, while transcellular fluid is the fluid that is contained in specialized cavities, such as cerebrospinal fluid, synovial fluid, or pleural fluid. The amount of transcellular fluid is normally very small compared to the interstitial fluid, but it can increase in certain conditions, such as edema, ascites, or hydrocephalus.