An example of capillary action is:

An example of capillary action is:

• A. The blood coursing through smaller veins
• B. Perfusion of mucus membranes
• C. The action of blood filling a hematocrit tube
• D. Removing serum from a clot with a pipette

Answer: (C)

Capillary action is the movement of liquid in a very narrow space driven by adhesive forces between the liquid and the surface plus cohesive forces within the liquid, enough to pull the liquid upward against gravity. In a hematocrit tube, the blood is drawn into the tiny glass tube by these capillary forces, so the sample fills the tube without needing a pump. This makes it a classic example of capillary action. The other scenarios describe circulation or manual transfer of serum, not capillary-driven rise in a narrow space.

Capillary action is the movement of liquid in a very narrow space driven by adhesive forces between the liquid and the surface plus cohesive forces within the liquid, enough to pull the liquid upward against gravity. In a hematocrit tube, the blood is drawn into the tiny glass tube by these capillary forces, so the sample fills the tube without needing a pump. This makes it a classic example of capillary action. The other scenarios describe circulation or manual transfer of serum, not capillary-driven rise in a narrow space.