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Blood and blood vessels. Home Blood and blood vessels. Circulatory system. Actions for this page Listen Print. Summary Read the full fact sheet. On this page. All cells in the body need to have oxygen and nutrients, and they need their wastes removed.
These are the main roles of the circulatory system. The heart, blood and blood vessels work together to service the cells of the body.
Using the network of arteries, veins and capillaries, blood carries carbon dioxide to the lungs for exhalation and picks up oxygen. From the small intestine, the blood gathers food nutrients and delivers them to every cell. Blood Blood consists of: Red blood cells — to carry oxygen White blood cells — that make up part of the immune system Platelets — needed for clotting Plasma — blood cells, nutrients and wastes float in this liquid.
The heart The heart pumps blood around the body. It sits inside the chest, in front of the lungs and slightly to the left side.
Gas and nutrient exchange with the tissues occurs within the capillaries that run through the tissues. Metabolic waste and carbon dioxide diffuse out of the cell into the blood, while oxygen and glucose in the blood diffuses out of the blood and into the cell. Systemic circulation keeps the metabolism of every organ and every tissue in the body alive, with the exception of the parenchyma of the lungs, which are supplied by pulmonary circulation.
The deoxygenated blood continues through the capillaries which merge into venules, then veins, and finally the venae cavae, which drain into the right atrium of the heart. From the right atrium, the blood will travel through the pulmonary circulation to be oxygenated before returning gain to the system circulation, completing the cycle of circulation through the body.
The arterial component of systemic circulation the highest blood pressures in the body. The venous component of systemic circulation has considerably lower blood pressure in comparison, due to their distance from the heart, but contain semi-lunar valves to compensate. Systemic circulation as a whole is a higher pressure system than pulmonary circulation simply because systemic circulation must force greater volumes of blood farther through the body compared to pulmonary circulation.
Learning Objectives Distinguish between the systemic and pulmonary circulation circuits. Key Points The cardiovascular system is composed of two circulatory paths: pulmonary circulation, the circuit through the lungs where blood is oxygenated, and systemic circulation, the circuit through the rest of the body to provide oxygenated blood. In the pulmonary circulation, blood travels through capillaries on the alveoli, air sacs in the lungs which allow for gas exchange.
Systemic and pulmonary circulation transition to the opposite type of circulation when they return blood to the opposite side of the heart.
Systemic circulation is a much larger and higher pressure system than pulmonary circulation. Key Terms alveoli : Air sacs in the lungs that provide the surface for gas exchange between the air and capillaries.
Here, oxygen and nutrients are released and carbon dioxide and other waste substances are absorbed. Deoxygenated blood then moves from the capillary beds through venules into the systemic veins. The systemic veins feed into the inferior and superior venae cavae, the largest veins in the body.
The venae cavae flow deoxygenated blood to the right atrium of the heart. See more from our free eBook library. A description of the vascular system from the edition of Gray's Anatomy of the Human Body. Functions of the Blood.
Anatomy of the Heart. Blood Vessels: The Circulatory Network. Circulatory System Pathologies. When you select "Subscribe" you will start receiving our email newsletter. Use the links at the bottom of any email to manage the type of emails you receive or to unsubscribe.
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