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Chapter 40

Chapter 40. Respiration. Respiration. Gas exchange (O 2 and CO 2 ) Diffusion down concentration gradient Specialized epithelial surfaces Moist Thin Large surface area. Respiration.

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Chapter 40

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  1. Chapter 40 Respiration

  2. Respiration • Gas exchange (O2 and CO2) • Diffusion down concentration gradient • Specialized epithelial surfaces • Moist • Thin • Large surface area

  3. Respiration • Fick’s Law—The larger the surface area and the steeper the partial pressure gradient, the faster diffusion will proceed. • Ventilation • Active movement of air • Necessary in larger animals • Enhances gas exchange rates

  4. Respiratory Pigments • Metal ions that bind to and carry O2 • Hemoglobin • All vertebrates; some mollusks, annelids, crustaceans • Iron ion • Oxygenated—red, deoxygenated—dark red • In all Kingdoms, but not all organisms • Structure of molecule varies by species

  5. Respiratory Pigments • Hemocyanin • Most mollusks, some arthropods • Copper ion • Oxygenated—blue, deoxygenated—colorless • Second most common pigment • Myoglobin • Found in muscle tissue • Can store O2 for later use • Amounts vary between species

  6. Invertebrate Respiration • Integumentary Exchange • Some aquatic animals • Small, simple organisms • Protozoans • Poriferans, Cnidarians, Platyhelminthes, Annelids, etc. • Short distance between O2 and tissues

  7. Invertebrate Respiration • Gills • Aquatic mollusks, arthropods • Different than fish • Outgrowth of body wall • Highly folded • Gas exchange to water

  8. Invertebrate Respiration • Book Lungs • Most arachnids • 1-4 pairs • Folded appearance • Direct opening outside of body

  9. Invertebrate Respiration • Tracheal System • Insects, millipedes, centipedes, some arachnids • Spiracles in integument • Tubes branch several times • Tips of finest branches end at body cells in all tissues

  10. Vertebrate Respiration • Gills • Aquatic vertebrates • Most internal • External in some fish larvae & amphibians • Finely branched • Attached to firm supports

  11. Vertebrate Respiration • Countercurrent Flow • Blood flows in opposite direction to water • Maximizes O2 exchange

  12. Vertebrate Respiration • Lungs • All terrestrial vertebrates, some fish • Saclike internal organ • Airways connect to external environment • Variable complexity

  13. Vertebrate Respiration • Amphibian respiration • Larvae gills, adults lungs • Some integumentary exchange • Frogs/toads take O2 through lungs, eliminate CO2 through skin • Small, simple lungs • Positive pressure • “Gulps” air into mouth • Pushes air into lungs • Body wall muscles contract, forcing air out of lungs

  14. Vertebrate Respiration • Reptile respiration • More developed lungs • Negative pressure • Draw air into lungs • Expansion & contraction of ribs causes ventilation

  15. Vertebrate Respiration • Avian respiration • Rigid lungs • No alveoli • Air sacs • Air flow continuously through lungs • Inhalation—air moves into posterior air sacs & lungs • Exhalation—air moves from air sacs into lungs, also exits lungs • Ventilate by expanding & contracting chest

  16. Vertebrate Respiration • Mammal respiration • Diaphragm • Contracts, pulling chest cavity down (negative pressure) • Relaxes, allowing outward flow • Ribcage can expand & contract • Exhalation not complete • O2-poor and O2-rich air mix

  17. Mammal/Human Respiration

  18. Mammal/Human Respiration • Alveous (pl. alveoli) • Only in mammals • Spherical sacs • Surrounded by capillaries • Simple squamous epithelium

  19. Respiratory Cycle • Inhalation • Ribs move out, diaphragm (if present) moves down • Increases thoracic volume • Draws air into lungs • Active, requires energy • Gas exchange • Exhalation • Intercostal muscles & diaphragm relax • Thoracic volume returns to normal • Reduction in volume forces air out • Passive, no energy required

  20. Special Situations • High altitude • Air pressure decreases w/ altitude • This decreases O2 transport • Hypoxia • Low blood O2 • Heart & respiratory muscles work harder • Hyperventilate • Animals • Hemoglobin has better affinity for oxygen • Carry more O2 at low pressure

  21. Special Situations • Humans born at high altitude • Lungs have more alveoli & blood vessels • Heart has larger ventricles to pump more blood • Muscles have more mitochondria • Humans born at low altitude • Can acclimate • Eventually produce more RBCs • Better oxygenation, but thicker blood

  22. Special Situations • Deep Sea • High pressure due to water volume • Forces nitrogen to be dissolved in tissues • Passes through cell membranes • If in neurons, disrupts signals • Nitrogen narcosis • When ascend, N2 moves into blood • If too rapid, bubbles form in blood • “The Bends” • Pain in joints, obstructed blood flow to organs

  23. Special Situations • Well-trained humans hold breath 3 min • Human records • Free-diving length: 9 min 8 sec • Free-diving depth: 244m (800’) • Deep-diving depth: 330m (1,082’) • 10m to reach depth • 8 hr 49 min to return to surface

  24. Special Situations • Animals • Sperm whale: 2500m (8,200’, 1.5mi), 1.5-2 hr • Leatherback sea turtle: 1,000m (3,280’), 30 min • Bottlenose dolphin: 550m (1,804’), 10 min

  25. Special Situations • How???? • Fill lungs fully before dive • 85-90% air exchange • Humans 15% • As dive lengthens, blood directed away from most organs • Preferentially to brain & heart • Myoglobin up to 10 times humans • 41% of O2 stored in muscles (humans 13%) • High lactic acid tolerance • Can operate in anaerobic metabolism longer • Mechanisms to avoid “bends” • Air w/ N2 taken at surface (lower pressure) • W/ depth, air moved to nonabsorptive areas, reducing gas exchange

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