The aortic valve separates the aorta and the left ventricle.īlood is the transport medium of nearly everything within the body. The pulmonic valve, or pulmonary valve, separates the pulmonary artery from the right ventricle. The remaining two valves are the semilunar valves. The mitral valve, or bicuspid valve, separates the left atrium from the left ventricle. The tricuspid valve separates the right atrium from the right ventricle. In the arms and legs, these valves make sure gravity doesn’t pull blood in the wrong direction. The valves in the medium and large veins keep the blood flowing towards the heart. The veins include valves, small pieces of tissue which keep blood flowing in the right direction. Veins have less pressure and can hold more blood than arteries.Īt any time, about 70 percent of the body’s total blood supply is in the veins.The walls of veins are thinner than artery walls.In veins, the walls have less smooth muscle and connective tissue.There are some important differences between the arteries and veins: Like the arteries, veins have walls made up of layers called the tunica intima, tunica media, and tunica externa. As the blood moves closer to the heart, the veins get larger and larger. The blood travels from the capillaries into the venules, which are the smallest veins. The blood moves back to the heart through veins. The cornea of the eye is one area that has no capillaries. Skeletal muscle, the liver, and the kidney all have a large number of capillaries because their body systems need a lot of oxygen and nutrients. ![]() The number of capillaries in a body system depends on the amount of material exchange. The capillaries connect the arteries, which take blood from the heart, and the veins, which take blood to the heart. The smallest arteries are the arterioles, which move blood from the muscular arteries to the capillaries. The femoral and coronary arteries are two examples of muscular arteries. They’re made of smooth muscle, which can expand and contract as blood flows. The muscular arteries move blood from the elastic arteries through the body. They’re the only arteries that carry deoxygenated blood. Pulmonary arteries take deoxygenated blood from the right ventricle to the lungs. The aorta is the body’s most important artery. They receive blood directly from the heart and need to be elastic to accommodate the surge and contraction as blood pushes through with each heartbeat. The aorta and pulmonary arteries are the elastic arteries. They get smaller and smaller the further they are from the heart. It’s made up of smooth muscle that changes the size of the artery to regulate blood flow. The middle layer is usually the thickest. The artery walls have three layers: tunica intima (inner), tunica media (middle), and tunica externa (outer). Join Seneca to get 250+ free exam board specfic A Level, GCSE, KS3 & KS2 online courses.Arteries carry blood away from the heart. Want to learn more about Double Circulatory System? ![]() The blood becomes deoxygenated and returns to the heart. The oxygenated blood gives its oxygen to body cells in exchange for carbon dioxide. This oxygenated blood is pumped out of the heart and to the body by the left ventricle. Oxygenated blood returns to the left atrium of the heart. This is how it becomes oxygenated (contains oxygen). This deoxygenated blood is pumped out of the heart and towards the lungs by the right ventricle.Īt the lungs, the deoxygenated blood exchanges carbon dioxide for oxygen. Circulatory System Diagramīlood Passes Through The Heart Twice Per Circuitĭeoxygenated blood from the body enters into the right atrium of the heart. By the time this blood returns to the heart, it has returned to a deoxygenated state. The left pump sends the newly oxygenated blood around the body. The right pump sends deoxygenated blood to the lungs where it becomes oxygenated and returns back to the heart. It is called a double circulatory system because blood passes through the heart twice per circuit. ![]() ![]() The human circulatory system has three key components: blood vessels, blood and the heart.
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