**Question:** The portal vein is related to all, except -

A. Liver
B. Small intestine
C. Pancreas
D. Stomach

**Core Concept:** The portal vein is a major vein in the human body responsible for carrying deoxygenated blood from the gastrointestinal tract to the liver. It plays a crucial role in the circulatory system by supplying nutrients, oxygen, and waste products to the liver and intestines.

**Why the Correct Answer is Right:** The correct answer, **D. Stomach**, is correct because the stomach is not directly connected to the portal vein. It is part of the gastrointestinal tract and is supplied with blood through the left gastric artery, which is a branch of the celiac trunk.

**Why Each Wrong Option is Incorrect:**

A. **Liver**: While the liver is connected to the portal vein, the question specifically mentions "except." The liver plays a vital role in detoxification, bile production, and glucose regulation, receiving blood from the portal vein.

B. **Small intestine**: The small intestine is connected to the portal vein, receiving nutrients and waste products from the absorbed food and digestion process.

C. **Pancreas**: The pancreas is indirectly related to the portal vein through the splenic vein, which drains blood from the pancreas into the portal vein.

**Clinical Pearl:** The portal vein system plays a significant role in the body's circulatory and digestive functions. Understanding its connections and roles in various organs helps in interpreting clinical cases involving liver, gastrointestinal tract, and pancreatic disorders.

**Correct Answer:** D. Stomach (as mentioned above)

**Explanation:** The portal vein system is responsible for supplying blood to the liver and small intestine, carrying essential nutrients, waste products, and oxygen from the gastrointestinal tract. The stomach, on the other hand, is supplied by the left gastric artery, which is a branch of the celiac trunk. This artery is separate from the portal vein system and provides blood to the stomach independently.