Chapter 42 - CR97-03

Chapter 42 - CR97-03 - Chapter 42 Circulation and Gas...

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Chapter 42 Chapter 42 Circulation and Gas Exchange 1 of 29 of 29
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Concept 42.1: Circulatory systems reflect Concept 42.1: Circulatory systems reflect phylogeny phylogeny Transport systems Internal transport systems circulate fluid & allow the aqueous environment of living cells to exchange chemicals with the outside environment Simple animals, such as cnidarians have a body wall only two cells thick that encloses a gastrovascular cavity The gastrovascular cavity functions in both digestion and distribution of substances throughout the body Some cnidarians have elaborate gastrovascular cavities 2 of 29 of 29
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Open and Closed Circulatory Systems Open and Closed Circulatory Systems 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) Blood bathes the organs directly in an open circulatory system Ex) In insects, other arthropods, and most molluscs In a closed circulatory system, blood is confined to vessels and is distinct from the interstitial fluid They’re more efficient at transporting circulatory fluids to tissues and cells Heart Hemolymph in sinuses surrounding ograns Anterior vessel Tubular heart Lateral vessels Ostia (a) An open circulatory system Figure 42.3a Interstitial fluid Heart Small branch vessels in each organ Dorsal vessel (main heart) Ventral vessels Auxiliary hearts (b) A closed circulatory system Figure 42.3b 3 of 29 of 29
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Arteries carry blood to capillaries Capillaries are the sites of chemical exchange between the blood and interstitial fluid Veins return blood from capillaries to the heart Fishes A fish heart has two main chambers One ventricle and one atrium Blood pumped from the ventricle travels to the gills, where it picks up O 2 and disposes of CO 2 Amphibians Frogs and other amphibians have a three - chambered heart, with two atria and one ventricle The ventricle pumps blood into a forked artery that splits the ventricle’s output into the pulmocutaneous circuit and the systemic circuit 4 of 29 of 29
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Reptiles (Except Birds) Reptiles have double circulation, with a pulmonary circuit (lungs) and a systemic circuit Turtles, snakes, and lizards have a three -chambered heart Mammals and Birds In all mammals and birds (and crocodiles) The ventricle is completely divided into separate right and left chambers The left side of the heart pumps and receives only oxygen-rich blood while the right side receives and pumps only oxygen-poor blood A powerful four-chambered heart was an essential adaptation of the endothermic way of life characteristic of mammals and birds 5 of 29 of 29
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42.2: Double circulation 42.2: Double circulation in mammals in mammals Mammalian Circulation Heart valves dictate a one-way flow of blood through the heart Blood begins its flow with the right ventricle pumping blood to the lungs In the lungs the blood loads O
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This note was uploaded on 04/07/2008 for the course BIO 103 taught by Professor Mannino during the Fall '08 term at Long Island U..

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Chapter 42 - CR97-03 - Chapter 42 Circulation and Gas...

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