Pressure gradients drive fluid filtration and reabsorption in capillaries Steps: - Identify flow directions: fluid exits capillary to tissue at arterial end (W to X), requiring higher pressure at W than X. - Identify return flow: fluid enters capillary from tissue at venous end (Y to Z), requiring higher pressure at Y than Z. - Note constant oncotic pressure (~26 mm Hg) pulls fluid in, decreasing hydrostatic pressure (~26 mm Hg arterial to 18 mm Hg venous) pushes fluid out initially. - Select option with 26 mm Hg > 18 mm Hg gradients at both ends for correct flow. Why B is correct: - B aligns with Starling's forces, where hydrostatic pressure exceeds opposing forces at arterial end (26 > 18 mm Hg for filtration) and oncotic exceeds hydrostatic at venous end (26 > 18 mm Hg for reabsorption). Why the others are wrong: - A: Reverses gradients (18 < 26 mm Hg), causing reabsorption at arterial end and filtration at venous end. - C: Incorrect arterial hydrostatic (36 mm Hg too high) and venous values mismatch standard drop to …