24. Tracing the drainage of venous blood from the small intestine, we find that blood enters the superior mesenteric vein, hepatic vein, inferior vena cava and right arrium. Which vessels are missing from that sequence? A. Coronary sinus and left atrium B. Celliac and common hepatic veins C. Internal and common iliac veins D. Hepatic portal vein and liver sinusoids

The correct answer is D. Hepatic portal vein and liver sinusoids.<br /><br />The sequence of blood flow from the small intestine is as follows:<br /><br />1. Blood from the small intestine drains into the superior mesenteric vein.<br />2. The superior mesenteric vein joins the inferior mesenteric vein to form the hepatic portal vein.<br />3. The hepatic portal vein carries the blood to the liver sinusoids.<br />4. Blood from the liver sinusoids drains into the hepatic veins.<br />5. The hepatic veins carry the blood to the inferior vena cava.<br />6. The inferior vena cava carries the blood to the right atrium of the heart.<br /><br />Therefore, the vessels missing from the given sequence are the hepatic portal vein and the liver sinusoids.