Kaplan Nursing Entrance Exam Practice 2025 – Comprehensive Prep

Fluid moves from the interstitial space to the intracellular space primarily through the processes of diffusion and osmosis.

To understand this process, it’s important to first recognize what the interstitial space and intracellular space are. The interstitial space is the area between cells, while the intracellular space refers to the fluid within the cells. When discussing fluid movement, osmosis is key; it involves the movement of water across a selectively permeable membrane (the cell membrane) from an area of lower solute concentration (interstitial fluid) to an area of higher solute concentration (inside the cell). This movement continues until the concentrations on both sides of the membrane reach equilibrium.

Diffusion also plays a role in the movement of small solutes and gases, which can pass more easily through the cell membrane. The combined action of osmosis and diffusion is essential for maintaining cellular hydration and nutrient balance.

In contrast, active transport involves the movement of substances against their concentration gradient, often requiring energy, while filtration typically refers to the movement of fluids through a membrane due to hydrostatic pressure. Pinocytosis, a form of endocytosis, involves the engulfing of liquid droplets by the cell membrane but does not primarily describe the movement of fluid between the interstitial