IMG_NEW_0002 - system of insects for gas transport to and...

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TECTURE 3: Respiration and Gas Exchange 1. Respiratory systems facilitate Oz and COz transfer As animals get larger, they must maximize SA to bring 02 in. Therefore, respiratory systems do several things to facilitate Oz uptake: increase SA decreases diffusion distance increase blood supply 2. Gas exchange organs reflect different respiratory media , Air ' Oz is plentiful {.21% at sea level) . is less dense and less viscous . breathing air is relatively easy and not that efficient (we extract only 25% of air we inhale) Water . contains 40 x less 02 as air (and much less at higher temPeratures and salinities) high density/viscosity = hard to move breathing in water in relatively energy- demanding; needs to be highly efficient 3. Trachea -network of tubes throughout insect body -tubes are kept from collapsing by thick rings of chitin -trachea branch into finer tracheoles, which supply individual cells -gas exchange occurs at the ends across moist membranes -compensates for inefficient open circulatory
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Unformatted text preview: system of insects for gas transport to and from tissues 3. Gills GILLS are an external organ and are very different from lungs due to the of nof t4., epithelium to increase SA. Site of gas exchange is the secondary lamella" n\ flfl ventilation is.tlNlglBECIloNAL due to properties of water Blood flow is COUNTERCURRENI Water and \----blood flow in opposite directions. This maintains a gradient along the gill exchange surface (secondary lamellae) and allows the almost complete transfer of 02 3. Lungs LUNGS are an organ of small volume which allows for: Q maximization of respiratory S.A. Qu"n small diffusion distance covered in rab handout. rib n"t'lo'*va J Mammals use negative-pressure breathing /P$c# 2d' f#;r air into rungs) and air no* iffi t^effiffi Automatic controlof breathing (Fig. a2.271 ;rkb*) . breathing is regulated by involuntary mechanisms \-__...
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This note was uploaded on 12/29/2011 for the course HSCI 160 taught by Professor Kreis during the Fall '10 term at Simon Fraser.

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