Blood vessels can be grouped into three categories: arteries, veins and capillaries. Arteries are the blood vessels that transfer blood away from the heart to the organs. They are the thickest of the blood vessels because they carry the blood under the greatest pressure. Veins carry blood from the organs and tissues to the heart. Veins are thinner than arteries since they carry less pressurized blood. Capillaries are small blood vessels that connect arteries and veins and allow diffusion of nutrients into tissue. The body is made up of a network of many blood vessels, however there are several that have the most significance.
Aorta
The aorta is an artery and the largest blood vessel in the body. It begins in the upper left ventricle of the heart and carries oxygenated blood to the tissues of the body, according to Anatomy of the Human Body. Since it is so large, it is broken into several portions: the ascending aorta, the arch of the aorta and the descending aorta, which is further divided into the thoracic and the abdominal aortae, according to Human Anatomy.
Coronary Arteries
The coronary arteries stem from the aorta. The two major coronary arteries are the right coronary artery and the left coronary artery. They bring blood to the heart, which supplies the cardiac tissue with the necessary oxygen and nutrients that is required for normal function.
Pulmonary Artery
The pulmonary artery is a large artery that divides into the left pulmonary artery and the right pulmonary artery. These arteries take blood away from the heart and bring it to the left and right lungs where it can be enriched with oxygen, according to Cleveland Clinic. The pulmonary artery branches off the right ventricle of the heart.
Superior and Inferior Vena Cava
The superior vena cava and the inferior vena cava are the two main veins responsible for carrying deoxygenated blood from the body to the heart. The superior vena cava empties blood from the head and upper torso into the right atrium of the heart. The inferior vena cava empties blood from the legs and lower torso into the left atrium of the heart, according to Cardiovascular Consultants.
Pulmonary Veins
The pulmonary veins carry blood rich with oxygen from the lungs to the left atrium of the heart. There are four pulmonary veins, two that stem from each lung, according to Anatomy of the Human Body.
