BIOL 11100 Lecture Notes - Lecture 20: Ectotherm, Circulatory System, Extracellular Fluid
14 Apr 2016
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Recall that small molecules (like o2 and co2) can move b/w cells and their surroundings via difusion. Net movement results when concentraion gradient results in net movement of molecules. Net movement of molecules is very slow, esp for distances greater than a few mm. Relaionship b/w difusion ime & distance puts constraint on animal body plans. Natural selecion resulted in 2 basic adaptaions that allow efecive exchange for all cells. Body size & shape that places many/all cells in direct contact w/ environment i. ii. Allows each cell to directly exchange w/ surroundings. Found only in invertebrates like cnidarians & latworms(relaively simple: a circulatory system i. ii. Moves luid b/w each cell"s immediate surroundings & body issues where exchange w/ environment occurs. In simple invertebrates w/o circulatory systems, this distributes molecules throughout the body. Oten combined w/ lat/n;;"arrow body to facilitate difusion w/ environment. Circulatory systems: 3 basic components: circulatory luid. Open circulatory system- found in arthropods & some molluscs.
