Blood vessels are the conduits through which our body transports blood. Arteries and veins are the types of blood vessels in the vascular system. Although they both carry blood, there is a big difference. Arteries and veins are made up of different tissues, each of which functions in a specific way. One of the most important differences is that all arteries output blood from the heart, while all veins input blood from other parts of the heart. The arteries follow the rhythm of the heartbeat (arterial muscle contraction) to transport blood rich in oxygen and nutrients to the whole body, and the veins collect deoxygenated blood rich in carbon dioxide and send it to the heart. What is more special is that the pulmonary artery carries deoxygenated blood. After the vein carries the blood from the body to the heart, it will be pumped into the lungs, and then the pulmonary veins will send the oxidized blood back to the heart from the lungs.
Many diseases of the human body are caused by blood vessels. Therefore, in medical teaching, medical students will use various vascular system anatomical specimens to understand the position and distribution of human blood vessels and the roles and division of labor of different blood vessels. In clinical medicine, veins are regarded as "access points" for human blood, such as injecting fluids or drawing blood.
