The circulatory system transports nutrients, gases, hormones, blood cells, and helps regulate body temperature throughout the body via blood circulation. It consists of blood vessels and muscles that control blood flow. Common diseases of the circulatory system include cardiomyopathy, hemophilia, pericarditis, angina, and atherosclerosis which involve issues like heart muscle weakening, impaired blood clotting, heart sac inflammation, chest pain from reduced blood flow, and artery narrowing from plaque buildup. Treatment depends on the specific condition but may include medications, medical procedures, or lifestyle changes.