What type of blood does the portal vein carry to the liver?

The portal vein carries deoxygenated blood that is rich in nutrients and toxins from the gastrointestinal tract and spleen to the liver. This blood is crucial because it contains substances absorbed from the digestive system, including nutrients from food, as well as metabolic waste and toxins that need to be processed by the liver.

The liver plays a vital role in filtering this blood, metabolizing nutrients, detoxifying harmful substances, and performing various other functions essential for maintaining homeostasis. Unlike systemic circulation, where oxygenated blood is delivered from the heart to the body, the portal circulation is specifically designed to ensure that the liver receives this nutrient-rich blood for processing before it enters the general circulation.

Therefore, the correct characterization of the type of blood carried by the portal vein focuses on its deoxygenated nature and its content of nutrients and toxins, reflecting the unique function of the portal venous system in digestion and metabolism.