Three main types of blood vessels make up the circulatory system that's powered by the pumping action of the heart: arteries, veins and capillaries. When freshly oxygenated blood leaves the heart, the arteries carry the oxygen and nutrients towards the rest of the body, then they divide into smaller arterioles and further connect to the capillaries, the main site of gas exchange. According to the Franklin Institute, arteries consist of three layers: outer layer, middle muscular layer and an inner smooth layer. Arteries are strong and elastic, built to withstand the pressure from the pumping heart.
At the Heart
Blood circulation divides into two parts: systemic circulation and pulmonary circulation. The pulmonary circulation functions to deliver deoxygenated blood from the veins, through the heart and into the lungs via the pulmonary artery and its branches so that it may be "recycled" and reoxygenated. The pulmonary artery is the only artery in the body that transports oxygen-poor blood. The Franklin Institute states blood pumps out of the heart to the rest of the body through the aorta, the main artery of the body. The arch of aorta located on top of the heart lead to the major arteries supplying the neck, head and upper extremities. The abdominal aorta supply the abdominal wall as well as lead to the arteries supplying all internal organs and lower extremities. The initial branches that stem from the aorta are the main coronary arteries which supply the heart muscle. These include the right coronary artery and the left main coronary artery, according to the Cleveland Clinic.
Above the Heart
The head and upper neck are supplied through the common carotid artery which further divides to internal and external carotids. In the head, the carotids branch off to smaller arteries to supply facial tissues and the brain. The main artery supplying the lower neck and upper extremities is the subclavian artery, which leads to the axillary artery in the armpit. From there, the brachial artery takes over supplying the upper arm, shoulder and the chest wall. At the bend of the elbow, the brachial artery branches into the radial and ulnar arteries extending down the lower arm. Additionally, both of these arteries make up a network of smaller digital arteries to supply the fingers.
Below the Heart
Within the trunk, smaller arteries branch off the abdominal aorta to supply each abdominal organ such as the stomach, liver, spleen, intestines and the kidney. According to CliffsNotes.com, these are the left and right gastric, common hepatic, splenic, superior mesenteric and renal arteries, respectively. In the hip region, the abdominal aorta divides into the common iliac artery--two branches supplying organs of the pelvic region and each of the lower limbs. The femoral artery running down the thigh is the main artery of the leg. At the knees, the popliteal artery extends down branching off into the anterior and posterior tibial arteries which supply muscles of the lower leg. The dorsalis pedis artery supplies the ankles and posterior foot, continuing to the arch of the foot artery which runs through the toes.
