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Respiratory Systems. Gas exchange involves uptake of O 2 and release of CO 2. What is oxygen used for?. Why the need for gas exchange (respiration)?. Aerobic respiration uses energy of electrons to produce ATP.
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Respiratory Systems • Gas exchange involves uptake of O2 and release of CO2 • What is oxygen used for? • Why the need for gas exchange (respiration)? • Aerobic respiration uses energy of electrons to produce ATP • Energy-depleted electrons (and associated proton in H) accepted by O2 to form H2O • Where does CO2 come from? • CO2 released when glucose broken down to release electrons in the Kreb’s Cycle How do organisms ‘solve’ common problems?
Respiratory Systems • Respiration requires diffusion of O2 and CO2 across cell membranes • Respiration involves diffusion • Diffusion of O2 and CO2 is passive • Occurs if different concentrations of O2 or CO2 on either side of membrane How do organisms ‘solve’ common problems?
Difference in concentration on either side of membrane Distance across which diffusion takes place Area over which diffusion takes place Diffusion constant Rate of diffusion (amount of gas per unit time) Respiratory Systems • Rate of diffusion described by Fick’s Law of Diffusion: • What determines rate of diffusion? How do organisms ‘solve’ common problems?
Respiratory Systems • How can rate of diffusion be maximized by natural selection? • R increased if: • Increase area (A) of respiratory surface • Increase difference in concentration (DP) on either side of respiratory surface • Decrease distance (d) over which gases must travel How do organisms ‘solve’ common problems?
Phyla Cnidaria Respiratory Systems • Direct diffusion through cells • Basic types of respiratory systems in animals • How to maximize rate of diffusion? • thin cell or tissue layers • circulate water across outer surface (maintain DP) • What constraints are associated with this system? • cannot be large in size • Cannot be involved in energy-consuming activities How do organisms ‘solve’ common problems?
Phyla Annelida Respiratory Systems • Cutaneous (skin) respiration • Basic types of respiratory systems in animals • How to maximize rate of diffusion? • thin skin • Increase surface area with parapodia • Use cilia on skin to move water (maintain DP) • What constraints are associated with this system? • cannot get too large • No energetically expensive activities How do organisms ‘solve’ common problems?
Respiratory Systems • External Gills • Basic types of respiratory systems in animals • Phylum Chordata • larval fish and amphibians (also in some adult salamanders) • How to maximize rate of diffusion? • thin gills • Increase surface area with feather-like arrangement of gills and by using skin as additional respiratory surface • What constraints are associated with this system? • Must be in constant motion or in water current • Tissue delicate and cannot be protected • Relatively small body size How do organisms ‘solve’ common problems?
Respiratory Systems • Neotenic salamander (development arrested in juvenile stage; adults have external gills) How do organisms ‘solve’ common problems?
Respiratory Systems • Internal (covered) Gills • Basic types of respiratory systems in animals • Phylum Chordata • Bony fish (Class Osteichthyes) • Internal gills enclosed within body chambers that move water over gills • Buccal cavity (mouth) • Opercular cavity (gill chamber below gill cover or operculum) • Two cavities act together to draw water across surface of gills How do organisms ‘solve’ common problems?
Respiratory Systems • Internal (covered) Gills • Basic types of respiratory systems in animals • How to maximize rate of diffusion? • thin gills (blood vessels close to surface of gill) • Increase surface area of gill with feather-like arrangement • Constantly ‘pump’ water across gills with buccal and opercular cavities • Uses counter-current system in gills to increase DP How do organisms ‘solve’ common problems?
Respiratory Systems • Structure of Internal Gills • Basic types of respiratory systems in animals How do organisms ‘solve’ common problems?
Respiratory Systems • Water flows over surface of lamellae of gills within which are capillaries • Basic types of respiratory systems in animals • flow of blood in capillaries is opposite flow of water = counter-current system of gas exchange How do organisms ‘solve’ common problems?
Respiratory Systems • Internal Gills • Basic types of respiratory systems in animals • What constraints are associated with this system? • Gills very efficient in water but do not work on land • Gills lack support needed in less-buoyant air • Air is relatively dry and all respiratory surfaces must be moist (gas exchange must occur in water); gills have large surface area exposed to dry air How do organisms ‘solve’ common problems?
