Which force pulls water from the interstitial space into capillaries due to plasma proteins?

Which force pulls water from the interstitial space into capillaries due to plasma proteins?

• A. Plasma oncotic pressure
• B. Hydrostatic pressure
• C. Osmotic pressure
• D. Hydrophilic force

Answer: (A)

Water movement across capillary walls is governed by Starling forces, where plasma proteins confined in the blood create a pulling force on water back into the vessels. This pulling force, caused by those proteins, is called plasma oncotic pressure (colloid osmotic pressure). It draws fluid from the interstitial space into the capillaries, helping to maintain blood volume. Hydrostatic pressure, in contrast, tends to push water out of the capillaries into the interstitial space. So while osmotic pressure is a general term describing water movement due to solute concentration, the specific force produced by plasma proteins is plasma oncotic pressure. Hydrophilic force isn’t a recognized driver of this process.

Water movement across capillary walls is governed by Starling forces, where plasma proteins confined in the blood create a pulling force on water back into the vessels. This pulling force, caused by those proteins, is called plasma oncotic pressure (colloid osmotic pressure). It draws fluid from the interstitial space into the capillaries, helping to maintain blood volume. Hydrostatic pressure, in contrast, tends to push water out of the capillaries into the interstitial space. So while osmotic pressure is a general term describing water movement due to solute concentration, the specific force produced by plasma proteins is plasma oncotic pressure. Hydrophilic force isn’t a recognized driver of this process.