BIO 126 Lecture Notes - Lecture 14: Purkinje Fibers, Hemorheology, Viscosity
21 Mar 2016
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Document Summary
Primary function of a circulatory system is: transport necessary materials to the cells of an animal"s body, transport waste products away from cells so they can be released into the environment. Food is digested in the cavity and absorbed into cells. Single opening serving as both mouth and anus. When the animal contracts its body, water is circulated through the gastrovascular cavity. Muscle contractions help to circulate waste and nutrients: open circulatory system. Hemolymph ( blood mixes directly with interstitial fluid) One or more heart: hemolymph is pumped into ostia and out open ended vessels to bathe tissues. Hemolymph cannot be selectively delivered to different tissues. Nutrients and waste exchange by diffusion: metabolically inexpensive. Hemolymph bathes tissues: closed circulatory system. Blood and interstitial fluid are physically separated. Larger, more active animals need a higher pressure to pump blood to all body cells. Found in earthworms, cephalopods, and all vertebrates. System grows in size as an animal grows.
