Which trio makes up the perfusion triangle?

• A. Plasma, red blood cells, platelets
• B. Arteries, veins, capillaries
• C. Heart, brain, lungs
• D. Heart, blood vessels, blood

Answer: (D)

The perfusion triangle is made of three interacting parts that must work together to deliver blood to tissues: the heart as the pump, the blood vessels as the conduits, and the blood as the flowing fluid. That’s why the trio including heart, blood vessels, and blood is the best fit. Without a functioning heart, there’s no pumping; without vessels, the blood can’t reach tissues; and without blood, there’s no fluid to carry oxygen and nutrients. The other options miss at least one of these essential components—blood components alone don’t include the pump and vessels, the vascular system alone isn’t the full trio, and organs aren’t the parts that constitute the perfusion mechanism.