Pulmonary circulation is that part of the circulation system which carries deoxygenated blood away from the right ventricle in heart to lungs and returns oxygenated blood from left atrium and ventricle to the heart.
A separate system called; Bronchial Circulation circulates this oxygenated blood to the tissues of larger airways to the lungs.
From the right atrium, the blood is pumped through the tricuspid valve (or right atrioventricular valve), into the right ventricle. Blood is then pumped from the right ventricle through the pulmonary valve and into the main pulmonary artery.
Here is a brief over view of how this system works:
The pulmonary arteries carry deoxygenated blood to the lungs, where carbon dioxide is released and oxygen is picked up during respiration. Arteries are further divided into very fine capillaries which are extremely thin-walled. The pulmonary vein returns oxygenated blood to the left atrium of the heart.
The oxygenated blood then leaves the lungs through pulmonary veins, which return it to the left part of the heart, completing the pulmonary cycle. This blood then enters the left atrium, which pumps it through the mitral valve into the left ventricle. From the left ventricle, the blood passes through the aortic valve to the aorta. The blood is then distributed to the body through the systemic circulation before returning again to the pulmonary circulation.
From the right
ventricle, blood is pumped through
the semilunar pulmonary valve into the left and right main pulmonary
arteries (one for each lung),
which branch into smaller pulmonary arteries that spread throughout the lungs.
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