Imbalance in Starling forces causing net filtration

Steps:

• Fluid exchange in capillaries follows Starling's hypothesis: net pressure = (hydrostatic pressure in capillary - hydrostatic in tissue) - (oncotic in capillary - oncotic in tissue).
• At arterial end, net filtration pushes fluid out; at venous end, net reabsorption pulls fluid in.
• Excess tissue fluid accumulates if reabsorption decreases or filtration increases.
• Higher small protein concentration in tissue fluid raises interstitial oncotic pressure, reducing reabsorption and increasing net fluid loss.

Why B is correct:

• Starling's equation shows increased interstitial oncotic pressure (π_i) widens the filtration gradient, leading to more fluid accumulation in tissues.

Why the others are wrong:

• A: Raises plasma oncotic pressure, enhancing reabsorption and reducing tissue fluid buildup.
• C: Decreases plasma concentration (likely proteins), lowering oncotic pressure and increasing filtration, but does not directly target tissue fluid dynamics.
• D: Lowers capillary hydrostatic pressure, decreasing overall filtration and tissue fluid accumulation.

Final answer: B