After studying this chapter you will be able to: Compare and contrast open and closed circulatory systems; compare and contrast the circulatory systems of fish, amphibians, reptiles, and mammals or birds; distinguish between pulmonary and systemic circuits and explain the function of each; trace the path of a red blood cell through the human heart, pulmonary circuit, and systemic circuit;. | Chapter 42 Circulation and Gas Exchange Overview: Trading with the Environment Every organism must exchange materials with its environment And this exchange ultimately occurs at the cellular level In unicellular organisms These exchanges occur directly with the environment For most of the cells making up multicellular organisms Direct exchange with the environment is not possible The feathery gills projecting from a salmon Are an example of a specialized exchange system found in animals Figure Concept : Circulatory systems reflect phylogeny Transport systems Functionally connect the organs of exchange with the body cells Most complex animals have internal transport systems That circulate fluid, providing a lifeline between the aqueous environment of living cells and the exchange organs, such as lungs, that exchange chemicals with the outside environment Invertebrate Circulation The wide range of invertebrate body size and form Is paralleled by a great diversity in circulatory systems Gastrovascular Cavities 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, such as jellies Have elaborate gastrovascular cavities Figure Circular canal Radial canal 5 cm Mouth Open and Closed Circulatory Systems More 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) In insects, other arthropods, and most molluscs Blood bathes the organs directly in an open circulatory system Heart Hemolymph in sinuses surrounding ograns Anterior vessel Tubular heart Lateral vessels Ostia (a) An open circulatory system Figure In a closed circulatory system Blood is confined to vessels and is distinct from the interstitial fluid . | Chapter 42 Circulation and Gas Exchange Overview: Trading with the Environment Every organism must exchange materials with its environment And this exchange ultimately occurs at the cellular level In unicellular organisms These exchanges occur directly with the environment For most of the cells making up multicellular organisms Direct exchange with the environment is not possible The feathery gills projecting from a salmon Are an example of a specialized exchange system found in animals Figure Concept : Circulatory systems reflect phylogeny Transport systems Functionally connect the organs of exchange with the body cells Most complex animals have internal transport systems That circulate fluid, providing a lifeline between the aqueous environment of living cells and the exchange organs, such as lungs, that exchange chemicals with the outside environment Invertebrate Circulation The wide range of invertebrate body size and form Is paralleled by a great diversity in circulatory
