How does water move between plasma and interstitial fluid?

Water movement between plasma (the liquid component of blood) and interstitial fluid (the fluid that surrounds cells) primarily occurs through osmosis and hydrostatic pressure.

Osmosis is the process by which water molecules move across a semi-permeable membrane, such as the capillary walls, from an area of lower solute concentration (interstitial fluid) to an area of higher solute concentration (plasma) to achieve equilibrium. This is crucial for maintaining proper fluid balance in the body.

Hydrostatic pressure plays a complementary role in this process by exerting force on the fluid in the capillaries. This pressure can drive water out of the plasma and into the interstitial space, particularly at the arterial end of capillaries, where blood pressure is higher. Conversely, at the venous end, osmotic pressure becomes more significant in pulling water back into the plasma from the interstitial fluid, ensuring that both compartments maintain a balance of fluids.

The other options do not accurately describe the primary methods of water movement between these two compartments. Active transport typically pertains to the movement of solutes rather than water, cellular division processes involve cellular reproduction rather than fluid movement, and direct cellular absorption is not a significant mechanism for water transfer between plasma