The largest reserve of blood of any body organ is contained in the:

• A. Kidneys
• B. Liver
• C. Spleen
• D. Pancreas

Answer: (B)

Think of the liver as a vast vascular reservoir. It has a dual blood supply—the hepatic artery and the portal vein—and its tissue is organized into extensive sinusoids that can hold a large volume of blood. This setup lets the liver store a substantial amount of circulating blood and rapidly release it when needed, such as during blood loss, helping to preserve blood pressure and perfusion. The spleen is also a blood reservoir, but its capacity is smaller than the liver’s. The kidneys receive a large portion of cardiac output for filtration, not storage, and the pancreas holds far less in reserve. So the largest reserve of blood in the body is contained in the liver.