The two circuits are linked to each other through the heart, creating a continuous cycle of blood through the body. Pulmonary circulation is the movement of blood from the heart to the lungs for oxygenation, then back to the heart again. Oxygen-depleted blood from the body leaves the systemic circulation when it enters the right atrium through the superior and inferior venae cavae. The blood is then pumped through the tricuspid valve into the right ventricle. From the right ventricle, blood is pumped through the pulmonary valve and into the pulmonary artery.
The pulmonary artery splits into the right and left pulmonary arteries and travel to each lung. At the lungs, the blood travels through capillary beds on the alveoli where gas exchange occurs, removing carbon dioxide and adding oxygen to the blood. Gas exchange occurs due to gas partial pressure gradients across the the alveoli of the lungs and the capillaries interwoven in the alveoli. The oxygenated blood then leaves the lungs through pulmonary veins, which returns it to the left atrium, completing the pulmonary circuit.
As the pulmonary circuit ends, the systemic circuit begins. Alveoli : A diagram of the alveoli, showing the capillary beds where gas exchange with the blood occurs. Case Files Collection. Clinical Sports Medicine Collection. Davis AT Collection.
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Next Chapter. AMA Citation Chapter 4. Blood Flow to the Lung. In: Levitzky MG. Levitzky M. Michael G. Pulmonary Physiology, 8e.
It sends oxygenated blood out to cells and returns deoxygenated blood to the heart. The heart pumps oxygenated blood out of the left ventricle and into the aorta to begin systemic circulation.
After the blood has supplied cells throughout the body with oxygen and nutrients, it returns deoxygenated blood to the right atrium of the heart. The deoxygenated blood shoots down from the right atrium to the right ventricle. The heart then pumps it out of the right ventricle and into the pulmonary arteries to begin pulmonary circulation. The blood moves to the lungs, exchanges carbon dioxide for oxygen, and returns to the left atrium.
The oxygenated blood shoots from the left atrium to the left ventricle below, to begin systemic circulation again. The circulatory and respiratory systems work together to sustain the body with oxygen and to remove carbon dioxide. Pulmonary circulation facilitates the process of external respiration: Deoxygenated blood flows into the lungs. It absorbs oxygen from tiny air sacs the alveoli and releases carbon dioxide to be exhaled. Systemic circulation facilitates internal respiration: Oxygenated blood flows into capillaries through the rest of the body.
The blood diffuses oxygen into cells and absorbs carbon dioxide. The subclavian arteries provide the blood supply for the upper extremity. The celiac, superior mesenteric, suprarenal, renal, gonadal, and inferior mesenteric arteries branch from the abdominal aorta to supply the abdominal viscera. Lumbar arteries provide blood for the muscles and spinal cord.
Branches of the external iliac artery provide the blood supply for the lower extremity. The internal iliac artery supplies the pelvic viscera. All systemic arteries are branches, either directly or indirectly, from the aorta.
The aorta ascends from the left ventricle, curves posteriorly and to the left, then descends through the thorax and abdomen.
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