Capillary blood is composed of which combination?

• A. Interstitial fluid, intracellular fluids, arterial and venous blood
• B. Plasma, red blood cells, white blood cells, and platelets
• C. Interstitial fluid and intracellular fluids, arterial and venous blood
• D. Lymph and tissue fluid

Answer: (C)

Capillary blood comes from the microcirculation where arterial and venous blood mix as it passes through the capillary beds. In this environment, you also have tissue fluids and the fluids inside cells contributing to what is carried along. So capillary blood isn’t just plasma or just cells from one side; it reflects a blend of arterial and venous blood plus the extracellular fluid around tissues (interstitial fluid) and the intracellular fluids contained within cells. That combination is captured by the option that includes interstitial fluid and intracellular fluids, along with arterial and venous blood, as the components of capillary blood. The other choices omit the mixed nature of capillary blood or mix in fluids that aren’t part of capillary blood in the same way.