Blood vessels - Anatomy and Function Fall 2023

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University Of Georgia *

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2210

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Anatomy

Date

Oct 30, 2023

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pdf

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Uploaded by EarlHornet3703

Dr. Crystal Robinson CBIO 2210 Fall 2023

▪ Describe the structure of a blood vessel. ▪ Describe the types of arteries, capillaries, and veins. ▪ Trace the general route usually taken by the blood from the heart and back again. ▪ Describe several variations in circuitry. ▪ Explain the relationship between blood pressure, resistance, and flow. ▪ Describe how blood pressure is measured and expressed. ▪ Show how pulse pressure and mean arterial pressure are calculated. ▪ Describe three factors that determine resistance to blood flow. ▪ Explain how vessel diameter influences blood pressure and flow. ▪ Describe some local, neural, and hormonal influences on vessel diameter.

▪ Three principal categories of blood vessels: • Arteries • Carry blood away from heart • Veins • Carry blood back to heart • Capillaries • Connect smallest arteries to smallest veins to create a circuit ▪ Figure 20.1 ▪ a: Dennis Strete/McGraw-Hill Education;b: Susumu Nishinaga/Science Source Saladin, Kenneth S. (2021). Anatomy & physiology : the unity of form and function (9th). Dubuque, IA: McGraw-Hill.

▪ Walls of arteries and veins have three layers (tunics): tunica interna, tunica media, tunica externa ▪ Tunica interna (tunica intima) • Lines the blood vessel and is exposed to blood • Endothelium • Simple squamous epithelium • Selectively permeable barrier • Secretes chemicals that stimulate dilation or constriction • Normally repels blood cells and platelets to prevent clotting • When tissue around vessel is inflamed, endothelial cells produce cell- adhesion molecules • Causes leukocytes to adhere to surface and congregate in tissues where their defensive actions are needed Venous system Large veins (capacitance vessels) Large lymphatic vessels Arterial system Arteriovenous anastomosis Lymphatic system Lymphatic capillaries Postcapillary venule Sinusoid Metarteriole Terminal arteriole Arterioles (resistance vessels) Muscular arteries (distributing arteries) Elastic arteries (conducting arteries) Heart Small veins (capacitance vessels) Lymph node Capillaries (exchange vessels) Precapillary sphincter Thoroughfare channel Marieb, E. and Keller, S., 2018. Essentials of Human Anatomy & Physiology . 12th ed. Pearson Education Limited.

▪ Tunica media • Middle layer • Consists of smooth muscle, collagen, and elastic tissue • Strengthens vessels and prevents blood pressure from rupturing them • Contraction of muscle controls blood vessel diameter ▪ Tunica externa (tunica adventitia) • Outermost layer • Consists of loose connective tissue that often merges with that of neighboring blood vessels, nerves, or other organs • Anchors the vessel and provides passage for small nerves, lymphatic vessels • Vasa vasorum: small vessels that supply blood to outer part of the larger vessels ▪ Figure 20.2 Saladin, Kenneth S. (2021). Anatomy & physiology : the unity of form and function (9th). Dubuque, IA: McGraw-Hill.

▪ Conducting (elastic or large) arteries • Biggest arteries • Examples: aorta, common carotid, subclavian, pulmonary trunk, and common iliac arteries • Internal elastic lamina at the border between interna and media • External elastic lamina at the border between media and externa • Expand during systole, recoil during diastole • Expansion takes pressure of smaller downstream vessels • Recoil maintains pressure during relaxation, keeps blood flowing Tunica media (smooth muscle and elastic fibers) • External elastic membrane Tunica externa (collagen fibers) • Vasa vasorum Artery Vein Lumen Lumen Valve Endothelial cells Basement membrane Capillary network Capillary Tunica intima • Endothelium • Internal elastic membrane • Subendothelial layer Marieb, E. and Keller, S., 2018. Essentials of Human Anatomy & Physiology . 12th ed. Pearson Education Limited.

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