Among the listed substances affecting fluid shifts, which is a gas?

Among the listed substances affecting fluid shifts, which is a gas?

• A. Oxygen
• B. Sodium
• C. Glucose
• D. Proteins

Answer: (A)

Fluid shifts are largely governed by osmosis and the forces created by solutes across membranes. Substances that contribute to osmotic or oncotic pressures—like sodium (an electrolyte), glucose (a solute that changes plasma osmolality), and proteins (which create oncotic pressure)—drive water movement between compartments. Gases, on the other hand, diffuse and don’t establish the same kind of sustained osmotic gradients that move water. Oxygen is a gas, whereas the others are solutes that influence water distribution through osmotic forces. So oxygen is the gas among the options.

Fluid shifts are largely governed by osmosis and the forces created by solutes across membranes. Substances that contribute to osmotic or oncotic pressures—like sodium (an electrolyte), glucose (a solute that changes plasma osmolality), and proteins (which create oncotic pressure)—drive water movement between compartments. Gases, on the other hand, diffuse and don’t establish the same kind of sustained osmotic gradients that move water. Oxygen is a gas, whereas the others are solutes that influence water distribution through osmotic forces. So oxygen is the gas among the options.