01:119:116 Lecture Notes - Lecture 27: Branchial Arch, Thoracic Cavity, Countercurrent Exchange
27 Apr 2016
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Document Summary
Po2=0. 21 x 760 = 160mmhg: gas- net diffusion, higher partial p lower partial p. Small aquatic organisms: <1mm thick, no circulatory or respiratory systems, simple diffusion, membranes in contacts w/ environment, ex. Respiratory structures: larger organisms- >1 mm thick, diffusion too slow, characteristics, gas exchange though air of h2o, features. Large surface area- rate of diffusion proportional to surface area. Moist- o2 and co2 dissolve in h2o before diffuses across respiratory surface. Blood vessels: 4 types, body surface, gills, tracheal tubes, lungs. Body surface: characteristics, simplest, small organisms- high sa to volume ratio, low metabolic rate, terrestrial moist environment, many also have gills or lungs, ex. Intro: most common in multicellular aquatic animals, gas exchange in h2o, evaginated exchange surfaces- extend out from body surface. Inner surface in contact w/ circulatory system: ventilation, mechanism to move air/h2o across a respiratory surface, fish. If h2o still, then o2 in water in contact w/ gills quickly depleted.
