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BIOLOGY CONCEPTS & CONNECTIONS Fourth Edition Neil A. Campbell • Jane B. Reece • Lawrence G. Mitchell • Martha R. Taylor CHAPTER 23 Circulation Modules 23.1 – 23.3 From PowerPoint® Lectures for Biology: Concepts & Connections Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings How Does Gravity Affect Blood Circulation? • As with all land animals, the giraffe and the corn snake are constantly subject to the force of gravity Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • The circulatory system keeps blood pumping despite gravity’s pull – Muscle contractions help blood travel uphill in the veins of a giraffe’s long legs – The wriggling of the corn snake squeezes its veins and increases circulation Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Most animals have a circulatory system – It transports O2 and nutrients to cells – It takes away CO2 and other wastes Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 23.1 The circulatory system associates intimately with all body tissues • Capillaries are microscopic blood vessels – They form an intricate network among the tissue cells Capillary Red blood cell Figure 23.1A Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings – No substance has to diffuse far to enter or leave a cell Capillary INTERSTITIAL FLUID Diffusion of molecules Tissue cell Figure 23.1B Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings MECHANISMS OF INTERNAL TRANSPORT 23.2 Several types of internal transport have evolved in animals • In cnidarians and flatworms, the gastrovascular cavity functions in both – digestion – internal transport Mouth Circular canal Figure 23.2A Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Most animals have a separate circulatory system, either open or closed • Open systems – A heart pumps blood through open-ended vessels into spaces between cells Tubular heart Pores Figure 23.2B Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Closed systems – A heart pumps blood through arteries and capillary beds – The blood returns to the heart via veins Capillary beds Arteriole Artery (O2-rich blood) Venule Vein Atrium Gill capillaries Artery Ventricle (O2-poor blood) Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Heart Figure 23.2C 23.3 Vertebrate cardiovascular systems reflect evolution Gill capillaries • A fish has a single circuit of blood flow Heart: Ventricle (V) Atrium (A) Systemic capillaries Figure 23.3A Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • The cardiovascular system of land vertebrates has two circuits Lung capillaries • The pulmonary circuit – conveys blood between the heart and gasexchange tissues PULMONARY CIRCUIT A • The systemic circuit – carries blood between the heart and the rest of the body A V Right V Left SYSTEMIC CIRCUIT Systemic capillaries Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 23.3B