There are three main types of blood circulation in the body: 1. Systemic circulation carries oxygenated blood from the heart to tissues throughout the body and returns deoxygenated blood to the heart. 2. Pulmonary circulation carries deoxygenated blood from the heart to the lungs, where carbon dioxide is released and oxygen is absorbed, before oxygenated blood returns to the heart. 3. Hepatic portal circulation involves the stomach, intestines, pancreas, spleen and liver. Blood is collected from these organs and transported via the portal vein to the liver before returning to systemic circulation.