circulatory system circulatory system the blood circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body of a human or other vertebrate. it includes the cardiovascular system, or vascular system, that consists of the heart and blood vessels (from greek kardia meaning heart, and from latin vascula meaning vessels). the circulatory system has two divisions, a systemic circulation or circuit, and a pulmonary circulation or circuit. some sources use the terms cardiovascular system and vascular system interchangeably with the circulatory system. circulatory systemthe human circulatory system (simplified). red indicates oxygenated blood carried in arteries. blue indicates deoxygenated blood carried in veins. capillaries join the arteries and veins.identifiersmeshd002319ta98a12.0.00.000ta23891fma7161anatomical terminology the network of blood vessels are the great vessels of the heart including large elastic arteries, and large veins; other arteries, smaller arterioles, capillaries that join with venules (small veins), and other veins. the circulatory system is closed in vertebrates, which means that the blood never leaves the network of blood vessels. some invertebrates such as arthropods have an open circulatory system. diploblasts such as sponges, and comb jellies lack a circulatory system. blood is a fluid consisting of plasma, red blood cells, white blood cells, and platelets that is circulated around the body carrying oxygen and nutrients to the tissues, and waste materials away. circulated nutrients include proteins and minerals, other components transported are gases such as oxygen, and carbon dioxide, hormones, and hemoglobin; providing nourishment, help in the immune system to fight diseases, and in maintaining homeostasis by stabilizing temperature and natural ph. in vertebrates, complementary to the circulatory system is the lymphatic system. this system carries excess plasma filtered from the capillaries as interstitial fluid between cells, away from the body tissues in an accessory route to return the excess fluid back to the blood circulation as lymph. the passage of lymph takes much longer than that of blood. the lymphatic system is a subsystem that is essential for the functioning of the blood circulatory system; without it the blood would become depleted of fluid. the lymphatic system works together with the immune system. unlike the closed circulatory system, the lymphatic system is an open system. some sources describe it as a secondary circulatory system. the circulatory system can be affected by many cardiovascular diseases. cardiologists are medical professionals which specialise in the heart, and cardiothoracic surgeons specialise in operating on the heart and its surrounding areas. vascular surgeons focus on disorders of the blood vessels, and lymphatic vessels. structure blood flow in the pulmonary and systemic circulations showing capillary networks in the torso sections the circulatory system includes the heart, blood vessels, and blood. the cardiovascular system in all vertebrates, consists of the heart and blood vessels. the circulatory system is further divided into two major circuits – a pulmonary circulation, and a systemic circulation. the pulmonary circulation is a circuit loop from the right heart taking deoxygenated blood to the lungs where it is oxygenated and returned to the left heart. the systemic circulation is a circuit loop that delivers oxygenated blood from the left heart to the rest of the body, and returns deoxygenated blood back to the right heart via large veins known as the venae cavae. the systemic circulation can also be defined as two parts – a macrocirculation and a microcirculation. an average adult contains five to six quarts (roughly 4.7 to 5.7 liters) of blood, accounting for approximately 7% of their total body weight. blood consists of plasma, red blood cells, white blood cells, and platelets. the digestive system also works with the circulatory system to provide the nutrients the system needs to keep the heart pumping. further circulatory routes are associated, such as the coronary circulation to the heart itself, the cerebral circulation to the brain, renal circulation to the kidneys, and bronchial circulation to the bronchi in the lungs. the human circulatory system is closed, meaning that the blood is contained within the vascular network. nutrients travel through tiny blood vessels of the microcirculation to reach organs. the lymphatic system is an essential subsystem of the circulatory system consisting of a network of lymphatic vessels, lymph nodes, organs, tissues and circulating lymph. this subsystem is an open system. a major function is to carry the lymph, draining and returning interstitial fluid into the lymphatic ducts back to the heart for return to the circulatory system. another major function is working together with the immune system to provide defense against pathogens. heart main article: heart diagram of the human heart showing blood oxygenation to the pulmonary and systemic circulation the heart pumps blood to all parts of the body providing nutrients and oxygen to every cell, and removing waste products. the left heart pumps oxygenated blood returned from the lungs to the rest of the body in the systemic circulation. the right heart pumps deoxygenated blood to the lungs in the pulmonary circulation. in the human heart there is one atrium and one ventricle for each circulation, and with both a systemic and a pulmonary circulation there are four chambers in total: left atrium, left ventricle, right atrium and right ventricle. the right atrium is the upper chamber of the right side of the heart. the blood that is returned to the right atrium is deoxygenated (poor in oxygen) and passed into the right ventricle to be pumped through the pulmonary artery to the lungs for re-oxygenation and removal of carbon dioxide. the left atrium receives newly oxygenated blood from the lungs as well as the pulmonary vein which is passed into the strong left ventricle to be pumped through the aorta to the different organs of the body. pulmonary circulation main article: pulmonary circulation the pulmonary circulation as it passes from the heart. showing both the pulmonary and bronchial arteries. the pulmonary circulation is the part of the circulatory system in which oxygen-depleted blood is pumped away from the heart, via the pulmonary artery, to the lungs and returned, oxygenated, to the heart via the pulmonary vein. oxygen-deprived blood from the superior and inferior vena cava enters the right atrium of the heart and flows through the tricuspid valve (right atrioventricular valve) into the right ventricle, from which it is then pumped through the pulmonary semilunar valve into the pulmonary artery to the lungs. gas exchange occurs in the lungs, whereby co2 is released from the blood, and oxygen is absorbed. the pulmonary vein returns the now oxygen-rich blood to the left atrium. a separate circuit from the systemic circulation, the bronchial circulation supplies blood to the tissue of the larger airways of the lung. systemic circulation capillary bed diagram of capillary network joining the arterial system with the venous system. the systemic circulation is a circuit loop that delivers oxygenated blood from the left heart to the rest of the body through the aorta. deoxygenated blood is returned in the systemic circulation to the right heart via two large veins, the inferior vena cava and superior vena cava, where it is pumped from the right atrium into the pulmonary circulation for oxygenation. the systemic circulation can also be defined as having two parts – a macrocirculation and a microcirculation. blood vessels the blood vessels of the circulatory system are the arteries, veins, and capillaries. the large arteries and veins that take blood to, and away from the heart are known as the great vessels. arteries main article: artery