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Respiratory Systems. Internal Gills . Respiratory systems in animals. How to maximize rate of diffusion? . Thin gills (blood vessels close to surface of gill). Feather-like structure increases surface area of gill. Constantly ‘pump’ water across gills.
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Respiratory Systems • Internal Gills • Respiratory systems in animals • How to maximize rate of diffusion? • Thin gills (blood vessels close to surface of gill) • Feather-like structure increases surface area of gill • Constantly ‘pump’ water across gills • Uses counter-current system in gills to increase DP • 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 • All respiratory surfaces must be moist; gills would have large surface area exposed to dry air How do organisms ‘solve’ common problems?
Respiratory Systems • Tracheae • Respiratory systems in animals • Phylum Arthropoda, Class Insecta • Air-filled passages carry gases directly to and from tissues • Air enters through spiracles in abdomen How do organisms ‘solve’ common problems?
Respiratory Systems • Tracheae • Respiratory systems in animals • How to maximize rate of diffusion? • Many spiracles increase surface area through which gas moves • Gases travel directly to tissues (small d) • What constraints are associated with this system? • Must remain small (maintain high surface area to volume) How do organisms ‘solve’ common problems?
Respiratory Systems • Lungs • Respiratory systems in animals • Phylum Chordata, Subphylum Vertebrata, Class Amphibia • Amphibian lungs are saclike pouches of digestive system • Surface area increased by folds of lung; less surface area than other vertebrates • use positive-pressurebreathing • fill buccal cavity with air • Close mouth and nostrils • Push floor of buccal cavity upward to push air into lungs How do organisms ‘solve’ common problems?
Respiratory Systems • Lungs • Respiratory systems in animals • Amphibian also use cutaneous respiration (particularly when active) • Amphibian lungs solve problems of gills: • Body supplies structural support for respiratory structures • Lung minimizes evaporation by moving air into body where it becomes saturated with water vapor • But relatively low surface area, positive-pressure breathing, and use of uniform pool of air not efficient • Constraints: small size, relatively low metabolic rates How do organisms ‘solve’ common problems?
Respiratory Systems • Lungs • Respiratory systems in animals • Phylum Chordata, Subphylum Vertebrata, Class Mammalia • Mammalian activities require more efficient respiratory systems • Lungs have alveoli (tiny clusters of sacs) to increase surface area • Capillary network on surface of thin-walled aveoli How do organisms ‘solve’ common problems?
Respiratory Systems • Lungs • Respiratory systems in animals • Mammalian activities require more efficient respiratory system • Negative-pressurebreathing • Diaphragm contracts causing the chest cavity to expand • Volume of lungs increases and air rushes in • More efficient than positive-pressure breathing How do organisms ‘solve’ common problems?
Respiratory Systems • Lungs • Respiratory systems in animals • Phylum Chordata, Subphylum Vertebrata, Class Aves • Most efficient respiratory system of all terrestrial vertebrates • Gas exchange in air vessels called parabronchi • Air moves through parabronchi in one direction only • No mixing of freshly inhaled air with old air not exhaled • Unidirectional flow of air requires use of airsacs (unique to birds) • Flow of blood 90o to flow of air in parabronchi (cross-currentflow); extract more O2 from air than mammals How do organisms ‘solve’ common problems?
Respiratory Systems • Respiratory system in birds (two-cycle respiration) • Respiratory systems in animals How do organisms ‘solve’ common problems?
Respiration in two cycles Respiratory Systems • Lungs • Respiratory systems in animals • Inhalation 1: air from outside goes to posterior air sacs • Exhalation 1: air from posterior air sacs to lungs • Inhalation 2: air from lungs to anterior air sacs • Exhalation 2: air from anterior air sacs leaves the body How do organisms ‘solve’ common problems?
Respiratory Systems • Review of variation in respiratory systems • Respiratory systems in animals How do organisms ‘solve’ common problems?
