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Explore the respiratory systems of selected aquatic creatures like fish, mollusks, and crabs, along with unicellular and small multicellular organisms. Learn about gill structures, blood and water flow, concurrent and countercurrent exchange, and adaptations for optimal oxygen acquisition. Delve into terrestrial respiratory organs like lungs in various animal groups and insect tracheal systems. Understand the mechanisms of respiration, gas exchange, and ventilation in both aquatic and terrestrial environments.
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Let’s Begin by Examining Respiratory Structures in Selected Aquatic Animals • Focus on structure and function • Focus on the diffusion rates and solubility characteristics of oxygen and carbon dioxide • Focus on supplemental means for acquiring sufficient oxygen
Respiration in Unicellular and Small MultiCellular Organisms
Crab Gill efferent vessel afferent vessel lamellae = blood flow = water flow branchial chamber
Concurrent Exchange Countercurrent Exchange 0 100 0 10 10 20 10 20 30 40 90 80 70 60 30 40 50 60 70 80 50 50 90 100
Concurrent Exchange PO2 Length Countercurrent Exchange PO2 Length
Ram ventilation - swimming with open mouth • Obligatory - e.g. some sharks and tuna • Facultative - e.g. mackerel - switch to ram • ventilation at swimming speeds • >0.5 - 1 m•s-1
Terrestrial Respiratory Structures Lungs Mollusca Crustacea Amphibia Reptilia Aves Mammalia Tracheae Insecta (no circulatory fluid involved - tubules branch and deliver air directly to tissues)
Open Spiracle in Grasshopper Closed Spiracle in Grasshopper
positive press. lungs e.g. amphibians suction lungs (subatmospheric press.) e.g. mammals Lungs diffusion lungs e.g. pulmonate snails ventilation lungs e.g. vertebrates
Mammalian Lung trachea pleural cavity bronchus lung diaphragm
air = = exterior intercostals - - diaphragm Inspiration
air Internal intercostals elastic recoil (surface tension) Expiration