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CHAPTER 14The Cardiovascular System: Blood Vessels

Copyright © 2007 by John Wiley & Sons, Inc.

Principles ofHuman Anatomy

Eleventh EditionGerard J. Tortora

&

Mark T. Nielsen

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ArteriesArteries Elastic or Conducting Arteries

Elastic fibers Stretch – stores potential energy Pressure reservoir Elastic recoil

Muscular or Distributing Arteries Smooth muscle Vasoconstriction/vasodilatation Regulate flow rates

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ArteriolesArteriolesVery small arteriesMuscular wallsSmooth muscleVasoconstriction/vasodilation

regulates blood flow into the capillary bed.

Play a major role in the regulation of blood pressure.

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CapillariesCapillaries Primary function is to allow exchange of

nutrients and wastes between the blood and tissues.

Found near all cells - Extensive branching networks

More abundant in highly metabolic tissues Tendons and ligaments – few Liver, kidney and lung – many

Single layer of epithelial cells + basement membrane

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VenulesVenules

Small veinsOnly scattered smooth muscle

cellsPlay a role in inflammatory

response

VeinsVeins

Thin tunica mediaTunica externa – thickest layerVery low blood pressureContain valves to prevent

backflowUse the skeletal muscle pump

15_0415_04 Blood DistributionBlood DistributionSystemic Venules and Veins – 60%Acts as a blood reservoir along with

liver, spleen and skinSystemic Arteries and Arterioles –

15%Systemic capillaries – 5%Pulmonary vessels – 12%Heart – 8%

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Learning ObjectivesLearning Objectives Discuss and compare the walls and layers

in arteries, veins, and capillaries Compare and contrast elastic and

muscular arteries Discuss the arterioles and their importance

in blood pressure Discuss the venules and veins Compare the relative blood volumes in the

different areas of the CV system