BSC 2086 01 Anatomy and Physiology II Spring 2013 9 Blood Vessels 2012 Pearson Education Inc An Introduction to Blood Vessels and Circulation Learning Outcomes 21 1 Distinguish among the types of blood vessels based on their structure and function and describe how and where fluid and dissolved materials enter and leave the cardiovascular system 21 2 Explain the mechanisms that regulate blood flow through vessels describe the factors that influence blood pressure and discuss the mechanisms that regulate movement of fluids between capillaries and interstitial spaces 2012 Pearson Education Inc An Introduction to Blood Vessels and Circulation Blood Vessels instrumental in overall cardiovascular regulation classified by size and histological organization Types of blood vessels 1 Arteries Carry blood away from heart 2 Arterioles Are smallest branches of arteries 3 Capillaries Are smallest blood vessels Location of exchange between blood and interstitial fluid 1 Venules Collect blood from capillaries 2 Veins Return blood to heart 2012 Pearson Education Inc 21 1 Blood Vessels The Largest Blood Vessels are attached to the heart They include 1 Pulmonary trunk Carries blood from right ventricle to pulmonary circulation 2 Aorta Carries blood from left ventricle to systemic circulation 2012 Pearson Education Inc 21 1 Blood Vessels The Smallest Blood Vessels are capillaries Have small diameter and thin walls Chemicals and gases diffuse across walls 2012 Pearson Education Inc 21 1 Blood Vessels The Structure of Vessel Walls Walls have three layers 1 Tunica intima 2 Tunica media 3 Tunica externa 2012 Pearson Education Inc 21 1 Blood Vessels 1 The Tunica Intima Inner 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 2012 Pearson Education Inc 21 1 Blood Vessels 2 The Tunica Media Middle Layer 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 2012 Pearson Education Inc 21 1 Blood Vessels 3 The Tunica Externa Outer Layer Anchors vessel to adjacent tissues in arteries Consists of 1 Collagen fibers 2 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 2012 Pearson Education Inc Figure 21 1 Comparisons of a Typical Artery and a Typical Vein Tunica externa Tunica media Tunica intima Smooth muscle Internal elastic membrane External elastic membrane Endothelium Elastic fiber Lumen of vein Lumen of artery ARTERY Artery and vein LM 60 2012 Pearson Education Inc Figure 21 1 Comparisons of a Typical Artery and a Typical Vein Tunica externa Tunica media Tunica intima Smooth muscle Endothelium Lumen of vein Lumen of artery Artery and vein LM 60 VEIN 2012 Pearson Education Inc Table 21 1 Key Terms and Relationships Pertaining to Blood Circulation 2012 Pearson Education Inc Table 21 1 Key Terms and Relationships Pertaining to Blood Circulation 2012 Pearson Education Inc Table 21 1 Key Terms and Relationships Pertaining to Blood Circulation 2012 Pearson Education Inc 21 1 Blood Vessels 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 2012 Pearson Education Inc 21 1 Structure and Function of Arteries Elasticity allows arteries to absorb pressure waves that come with Arteries each heartbeat Contractility Arteries change diameter Controlled by sympathetic division of ANS Vasoconstriction The contraction of arterial smooth muscle by the ANS Vasodilation The relaxation of arterial smooth muscle Enlarging the lumen 2012 Pearson Education Inc 21 1 Structure and Function of Arteries Vasoconstriction and Vasodilation Affect 1 Afterload on heart 2 Peripheral blood pressure 3 Capillary blood flow 2012 Pearson Education Inc 21 1 Structure and Function of Arteries Arteries From heart to capillaries arteries change From elastic arteries To muscular arteries To arterioles 2012 Pearson Education Inc 21 1 Structure and Function of Arteries 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 Stretches when ventricles contract pushing blood into vessel recoils to normal state when ventricles relax recoil allows blood to retain pressure 2012 Pearson Education Inc 21 1 Structure and Function of Arteries Muscular Arteries Also called distribution arteries Are medium sized most arteries Tunica media has many smooth muscle cells 2012 Pearson Education Inc 21 1 Structure and Function of Arteries Arterioles Are small arteries Have little or no tunica externa Have thin or incomplete tunica media 2012 Pearson Education Inc 21 1 Structure and Function of Arteries Artery Diameter Small muscular arteries and arterioles Change with sympathetic or endocrine stimulation Constricted arteries oppose blood flow creates Resistance R arterioles are also known as Resistance vessels 2012 Pearson Education Inc 21 1 Structure and Function of Arteries Aneurysm A bulge in an arterial wall Caused by weak spot in elastic fibers Pressure may rupture vessel if elastic component fails 2012 Pearson Education Inc Figure 21 2 Histological Structure of Blood Vessels Elastic Artery Medium Sized Vein Muscular Artery Large Vein Tunica externa Tunica media Endothelium Tunica intima Tunica externa Tunica media Endothelium Tunica intima Venule Tunica externa Endothelium Internal elastic layer Endothelium Tunica intima Tunica media Tunica externa Tunica externa Tunica media Endothelium Tunica intima Arteriole Smooth muscle cells Media Endothelium Basement membrane Fenestrated Capillary Capillaries Continuous Capillary Pores Endothelial cells Endothelial cells Basement membrane Basement membrane 2012 Pearson Education Inc Figure 21 2 Histological Structure of Blood Vessels Large Vein Tunica externa Tunica media Endothelium Tunica intima Tunica externa Tunica media Endothelium Tunica intima Venule Medium Sized Vein Tunica externa Endothelium 2012 Pearson Education Inc Figure 21
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