Lec17.respiration - BIOLOGY 325H Respiratory systems, Part...

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BIOLOGY 325H Respiratory systems, Part I Comparative and functional anatomy February 25, 2008 Most animal species have a dedicated respiratory system whose dual function is to absorb O 2 from the surrounding environment and to release the CO 2 that builds up in body tissues as a wasteproduct of oxidative metabolism. In today’s lecture we will focus on the anatomy of respiratory systems in different animal groups, and in the next lecture we will look more closely at the physiology and biochemistry of gas exchange. Respiratory organs have evolved independently in many animal groups, and it is important to appreciate that different kinds of respiratory systems have evolved to meet different environmental conditions. One extremely important factor is the chemical nature of the animal’s respiratory medium. Air-breathing animals exchange O 2 /CO 2 with the atmosphere, which is roughly 20% O 2 and – being a gas – takes relatively little work to move past the respiratory surface. In contrast, those animal species that did not evolve from air-breathing ancestors exchange O 2 /CO 2 with water, in which only a small amount of O 2 can dissolve. Moreover, the much greater density of water means that the animal must expend considerable energy to insure that this medium flows continuously past the respiratory surface. After considering the anatomy of some diverse respiratory systems, we will focus on two examples within the vertebrate animals: the gills of fish, which are adapted for respiration in water, and the lungs of tetrapod vertebrates, which are adapted for air-breathing. Learning Goals 1. Learn the basic features of all respiratory surfaces - i.e. large surface area for gas exchange; short distance for O 2 diffusion between the respiratory medium and either tissue cells or blood. How do these anatomical features relate to Fick’s Law of Diffusion?
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This note was uploaded on 04/07/2008 for the course BIO 325H taught by Professor Staff during the Spring '08 term at University of Texas at Austin.

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Lec17.respiration - BIOLOGY 325H Respiratory systems, Part...

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