[Campbell Biology P.981] According to the 'Capillary Function' section, which of the followi... | Practice Question

According to the 'Capillary Function' section, which of the following statements about capillary blood flow and substance exchange are TRUE? Select all that apply

  • A: At any given time, the majority of the body's capillaries are actively engaged in blood flow.
  • B: Blood supply to capillaries in organs like the brain, heart, kidneys, and liver typically remains at capacity.
  • C: Macromolecules primarily diffuse across the endothelial cells of capillaries.
  • D: The movement of fluid out of capillaries into surrounding tissues is mainly driven by blood pressure.
  • E: Histamine released at a wound site causes vasoconstriction, leading to reduced blood flow and white blood cell access.

Explanation

The text states that 'Capillaries in the brain, heart, kidneys, and liver usually remain at capacity'. It also notes that 'bulk flow of fluid into tissues driven by blood pressure within the capillary'. For A, only 5-10% of capillaries are active. For C, macromolecules use endocytosis/exocytosis, not diffusion. For E, histamine causes vasodilation, not vasoconstriction.