21_LectureOutline

21_LectureOutline - Classes of Blood Vessels Arteries Carry...

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Classes of Blood Vessels Arteries Carry blood away from heart Arterioles Are smallest branches of arteries Capillaries Are smallest blood vessels Location of exchange between blood and interstitial fluid Venules Collect blood from capillaries Veins Return blood to heart Blood Vessels The Largest Blood Vessels Attach to heart Pulmonary trunk Carries blood from right ventricle To pulmonary circulation Aorta Carries blood from left ventricle To systemic circulation The Smallest Blood Vessels Capillaries Have small diameter and thin walls Chemicals and gases diffuse across walls The Structure of Vessel Walls Walls have three layers: Tunica intima Tunica media Tunica externa The Tunica Intima Is the innermost layer Includes The endothelial lining Connective tissue layer Internal elastic membrane : in arteries, is a layer of elastic fibers in outer margin of tunica intima The Tunica Media Is the middle layer
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Contains concentric sheets of smooth muscle in loose connective tissue Binds to inner and outer layers External elastic membrane of the tunica media Separates tunica media from tunica externa The Tunica Externa Is outer layer Contains connective tissue sheath Anchors vessel to adjacent tissues in arteries Contain collagen Elastic fibers In veins Contains elastic fibers Smooth muscle cells Vasa vasorum (“vessels of vessels”) Small arteries and veins In walls of large arteries and veins Supply cells of tunica media and tunica externa Differences between Arteries and Veins Arteries and veins run side by side Arteries have thicker walls and higher blood pressure Collapsed artery has small, round lumen (internal space) Vein has a large, flat lumen Vein lining contracts, artery lining does not Artery lining folds Arteries more elastic Veins have valves Structure and Function of Arteries Arteries and Pressure Elasticity allows arteries to absorb pressure waves that come with each heartbeat Contractility Arteries change diameter Controlled by sympathetic division of ANS Vasoconstriction : the contraction of arterial smooth muscle by the ANS Vasodilatation : the relaxation of arterial smooth muscle enlarging the lumen Vasoconstriction and Vasodilation Affect Afterload on heart Peripheral blood pressure
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Capillary blood flow Arteries From heart to capillaries, arteries change From elastic arteries To muscular arteries To arterioles Elastic Arteries Also called conducting arteries Large vessels (e.g., pulmonary trunk and aorta) Tunica media has many elastic fibers and few muscle cells Elasticity evens out pulse force Muscular Arteries Also called distribution arteries
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21_LectureOutline - Classes of Blood Vessels Arteries Carry...

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