BIOL 206 Lecture Notes - Lecture 13: Truncus Arteriosus, Sinus Venosus, Gastrovascular Cavity
Document Summary
Both plants and animals have tissue specializations for transport: plants utilize a passive mode for transporting solutions, often producing high pressure potentials within rigid conducting elements: Xylem-dependent phloem-loading: animals use an active mode, and non-rigid conducting elements: Animals also maintain water balance for similar reasons: support, chemical reactions, temperature control, transport of solutes distinct pathways. A branching gastrovascular cavity serves as a circulatory system. Animal circulation requires muscle contraction to produce a positive pressure potential: note that the coelom in arthropods is present, but much reduced. Pumps compress on contents to produce positive pressure: peristaltic e. g. sea squirts; insects; worms, contractile chamber e. g. vertebrate and invertebrate branchial hearts, tube chamber with separate muscles e. g. vertebrate veins. The dilemma of pump placement in circulation: two alternative adaptations, both create challenges: If the pump is used to deliver body fluid with force to the gas exchange organ, little force remains to distribute the oxygenated fluid to the rest of the body tissues.
