Biol172_chapter42_2009

Biol172_chapter42_2009 - 3/11/2009 Chapter 42 CIRCULATION...

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3/11/2009 1 Chapter 42 CIRCULATION AND GAS EXCHANGE Circulatory systems reflect phylogenetic history • Most complex animals have internal transport systems circulate fluid providing a lifeline circulate fluid, providing a lifeline between the aqueous environment of living cells and the organs that exchange chemicals with the outside environment Lungs, gills Open and Closed Circulatory Systems • Complex animals have one of two types of circulatory systems: – open or closed • Both of these types of systems have three basic components – A circulatory fluid (blood) – A set of tubes (blood vessels) – A muscular pump (the heart) Hoses Pump Valve Fluid In insects, other arthropods, and most mollusks blood ( hemolymph ) bathes the organs directly in an open circulatory system Heart Hemolymph in sinuses di open circulatory system surrounding organs Anterior vessel Tubular heart Lateral vessels Ostia In a closed circulatory system blood is confined to vessels and is distinct from the interstitial fluid Interstitial Heart Small branched vessels fluid in each organ Dorsal vessel (main heart) Ventral vessels Auxiliary hearts Closed circulatory system
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3/11/2009 2 Survey of Vertebrate Circulation • Humans and other vertebrates have a closed circulatory system – Often called the cardiovascular system • Blood flows in a closed cardiovascular system consisting of blood vessels and a chambered heart • 2-4 chambers Survey of Vertebrate Circulation • Arteries carry blood to capillaries – The sites of chemical exchange between the blood and interstitial fluid • Veins return blood from capillaries to the heart Artery Vein VEINS ARTERIES Survey of Vertebrate Circulation • arteries carry oxygenated blood from the heart to the organs (other than lungs/gills) • Veins return deoxygenated blood from organs to the heart However: • arteries carry de-oxygenated blood from the organs to the lungs/gills • Veins return oxygenated blood from lungs/gills back to the heart! Advanced animals have double circulation
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3/11/2009 3 The Mammalian Heart • A closer look at the mammalian heart provides a better understanding of how double circulation works • The mammalian heart is four-chambered • Two atria (sing.: atrium ) Two (sing.: • Two ventricles • Separated by mitral valves • Prevent mixing and reflux • Two separate circulation systems for (1) the lungs and (2) the rest of the body FISHES AMPHIBIANS REPTILES (EXCEPT BIRDS) MAMMALS AND BIRDS Lung capillaries Lung capillaries Lung and skin capillaries Gill capillaries Vertebrate circulatory systems Systemic capillaries Systemic circulation Vein Atrium (A) Heart: ventricle (V) Artery Gil circulation Figure 42.4 Double circulation in mammals depends on the anatomy and pumping cycle of the heart Pulmonary artery Capillaries of left lung Capillaries of head and forelimbs Anterior vena cava Pulmonary artery Capillaries of right lung Aorta Pulmonary vein Right atrium Right ventricle Posterior vena cava Aorta Left ventricle Left atrium
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Biol172_chapter42_2009 - 3/11/2009 Chapter 42 CIRCULATION...

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