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Lecture 20, 06 Nov 2003 Chapter 13, Respiration, Gas Exchange, Acid-Base Balance

1. Lecture 20, 06 Nov 2003 Chapter 13, Respiration, Gas Exchange, Acid-Base Balance Chapter 14, Osmoregulation and Kidney Function Vertebrate Physiology ECOL 437 University of Arizona Fall 2003 instr: Kevin Bonine t.a.: Bret Pasch. 2. Vertebrate Physiology 437. 1. Blood-Gas Chemistry

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Lecture 20, 06 Nov 2003 Chapter 13, Respiration, Gas Exchange, Acid-Base Balance

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  1. 1 Lecture 20, 06 Nov 2003 Chapter 13, Respiration, Gas Exchange, Acid-Base Balance Chapter 14, Osmoregulation and Kidney Function Vertebrate Physiology ECOL 437 University of Arizona Fall 2003 instr: Kevin Bonine t.a.: Bret Pasch

  2. 2 Vertebrate Physiology 437 1. Blood-Gas Chemistry (CH13) 2. Osmoregulation Kidney Function (CH14) 3. Announcements… -No lecture Tues? -mini-lecture Wed.? -Eldon Braun Thurs.

  3. 3 Name that student: Alana_Kurosaki population genetics Amber_Blythe formerly with cast Ben_Abt dentist-to-be

  4. 4 Research/Laboratory Aide - Job number 27067 (http://www.hr.arizona.edu/27067xrsxptxoutx.htm)5 positions available, 40 hours per week, $9.02 per hourPosition Summary:This position assists in collecting small mammal and invertebrate data at Fort Huachuca Military Reservation in southeastern Arizona. The research project involves investigating fire-based restoration of biodiversity in grassland ecosystems. Study plots are located at approximately 4,400-4,900 feet elevation. Duties and Responsibilities:Traps small mammals and invertebrates on established study plots at Fort Huachuca. Collects and records data accurately on captured small mammals, including species identification, body measurements, sex determination, etc. Processes captured invertebrate specimens and accurately records data. Helps maintain field supplies. Assists with some computer data entry and/or proofing. To apply:Please submit an official University of Arizona job specific application (found at: http://www.hr.arizona.edu/01_rec/forms/empapplication.pdf) by mail or fax to: The University of Arizona - Human Resources 888 N. Euclid Avenue, #114P.O. Box 210158Tucson, Arizona 85721-0158 Fax: (520) 621-9098Customer Service: (520) 621-3660Please reference job number 27067 and Research/Laboratory Aide as the job title on your application materials.Review of materials will begin 12/1/03 and will continue until positions are filled.NOTE: Human Resources currently is unable to accept application materials via e-mail or the internet.

  5. 5 CO transport in blood 2 carbonic acid bicarbonate CO2 + H2O H2CO3 H+ + HCO-3 HCO-3 H++ CO2-3 carbonate CO2 + OH- HCO-3 Proportions of CO2 , HCO-3 depend on pH, T, ionic strength of blood At normal pH, Temp: 80% of CO2 in form of bicarbonate ion HCO-3 5-10% dissolved in blood 10% in form of carbamino groups (bound to amino groups of hemoglobin)

  6. CO2 transfer at tissue 6 -Chloride Shift -Carbonic Anhydrase • enters/leaves blood as CO2 (more rapid diffusion) • passes thru RBCs • CO2 produced = O2 released  no change in pH Band III protein oxygenation of hemo: acidify interior (release H+ ) maintain charge balance only in RBC, not plasma deox of hemo: increase pH (bind H+) (13-10)

  7. 7 Jacob-Stewart Cycle (13-17) Move acid in or out of RBC (e.g., help buffer CO2 rise in plasma)

  8. 8 Lung Ventilation (13-23)

  9. 9 Panting Dogs? Shakes 2002 Knut Schmidt_Nielsen 1972

  10. 10 Mammalian Ventilation -lungs are elastic bags -suspended in pleural cavity within thoracic cage (ribs and diaphragm define, fluid lining) -low volume pleural “space” between lung and thoracic wall -negative pressure to inflate lungs (increase volume) -pneumothorax

  11. 11 Mammalian Ventilation (13-28)

  12. 12 Mammalian Ventilation -expiration usually passive (13-30)

  13. 13 Mammalian Lung Alveoli and Capillaries RBC(not to scale) Knut Schmidt_Nielsen 1997

  14. 14 Pulmonary Surfactants -Reduce liquid surface tension in alveoli -Allows for compliance and low-cost expansion of lung -Lipoproteins -keep alveoli from getting stuck closed Atelectasis = collapsed lung -premature babies may need artificial surfactant

  15. 15 Frog Ventilation -Positive pressure ventilation 1. Into mouth (buccal cavity) 2. Close nares, open glottis and force air into lungs by raising buccal floor (13-33)

  16. 16 Knut Schmidt_Nielsen 1972 Mammal Lung Alveoli Bird Lung Parabronchi

  17. 17 Bird Ventilation -lung volume changes very little, air sacs instead (13-32) Unidirectional (13-32)

  18. 18 Bird Lung Ventilation Unidirectional!! ~ Continuous ventilation Knut Schmidt_Nielsen 1997

  19. 19 Relative Gill Surface Area in Fishes Knut Schmidt_Nielsen 1997

  20. 20 Fish Gill Knut Schmidt_Nielsen 1997

  21. 21 Fish Gill -breathing in water -need much higher ventilation rate -unidirectional -pump water across gills (or ram ventilation) Knut Schmidt_Nielsen 1997 (see your figure 13-40)

  22. 22 Lake Titicaca Frog (Bolivian Navy; Peru-Bolivia border) Knut Schmidt_Nielsen 1997

  23. 23 Rate and Depth Regulation -Primarily via CO2 changes (central) -Peripheral Chemoreceptors PO2, PCO2, pH -Innervate Medullary Respiratory Center (phrenic nerve to diaphragm and intercostals) -Emotions, sleep, light, temperature, speech, volition, etc. (13-46) -O2 controls respiration in aquatic vertebrates

  24. 24 Rate and Depth Regulation (13-48) Long term -Central Chemoreceptors

  25. 25 To Diaphragm alveolar (13-45)

  26. 26 Hering-Breuer reflex • Stimulation of stretch receptors inhibits medullary inspiratory center -Prevent overinflation -Ectotherms often breathe intermittently

  27. 27 1 2 2 1 To Diaphragm (13-45)

  28. 28 Extreme Conditions Student - Hypoxia, non-aquatic responses (e.g., altitude) I: • Drop in blood PO2 stimulates chemoreceptors  increased lung ventilation • But this increases CO2 elimination and pH increases, leading to reduced ventilation • Over time (a week), bicarbonate released to bring pH back down even with increased ventilation • Chemoreceptors reset to higher pH/lower CO2 • Hb with increased affinity for O2 • DPG levels increased to maintain Hb ability to unload O2at tissues (reduced Hb O2 affinity)

  29. 29 Extreme Conditions Student - Hypoxia, non-aquatic responses (e.g., altitude) II: • Systemic vasodilation and increased cardiac output (short-term) • Blood volume increases by 1/3 (chronic hypoxia) • Increase number of RBCs via erythropoietin (produced in liver in kidney in response to low blood PO2) action on bone marrow • Vascular endothelial growth factors increase capillary density • Pulmonary vasoconstriction leads to: • 1. increased pulmonary BP • 2. hypertrophied right ventricle • 3. large lung to body ratio

  30. 30 Student Oxygen dissociation curves and altitude Knut Schmidt_Nielsen 1997

  31. 31 Chapter 14 Osmoregulation -Ionic and Osmotic Balance -Kidney Function

  32. 32 Osmoregulation -life arose in salty sea -extracellular fluids ~ similar -dist’n limited by temperature and osmotic pressure (dehydration, ionic composition) -terrestrial organisms (and their descendents) regulate internal environment (homeostasis) -salt and water regulation (waste excretion) -kidneys, salt glands, gills

  33. 33 Obligatory Osmotic Exchanges 1-Gradients -Frog in freshwater -Fish in ocean 2-Surface-to-Volume Ratio -Small animals dehydrate or hydrate more rapidly -Skin, and Respiratory surface (higher metabolism with higher per/gram respiratory surface) 3-Integument Permeability -Transcellular or Paracellular -Aquaporins = water channel proteins -Frogs vs. Lizards, Pelvic Patch etc.

  34. 34 Obligatory Osmotic Exchanges 4-Feeding, Metabolism, Excretion -metabolic waste products ammonia, urea, etc. -metabolic water (desert!) -ingestion of salts -kidneys, salt glands, gills (more later) 5-Respiration -internalize respiratory surface -temporal countercurrent system (dry and cool IN, becomes moist and warm; recover) (countercurrent blood flow also) -temperature regulation vs. water conservation -ectotherm vs. endotherm (in deserts)

  35. 35 Osmoregulation -Water Breathing 1. Fresh Ambystoma tigrinum Blood osmolarity 200-300 mosm/L Water ~ 50 mosm/L - hyperosmotic animals, danger of swelling, losing salts - get their water across skin - dilute urine - active uptake of salts across epithelium - fish gills, frog skin, etc.

  36. 36 Osmoregulation -Water Breathing 2. Salt (~1,000 mosm/L) Most marine vertebrates hypo-osmotic (e.g., teleost or bony fishes) - danger of losing water, gaining too many salts - drink saltwater - excess salts actively secreted (gills, kidneys) • chloride cells for salt secretion • (Pelis et al. paper)

  37. 37 Osmoregulation -Air Breathing Have to lose water to allow gas exchange - Marine reptiles and marine birds can drink seawater and secrete salts in high [ ] - SALT GLANDS - Mammals rely on kidney (14-8)

  38. 38 Osmoregulation -Air Breathing Desert Mammals Behavior and Physiology (14-9) • Kangaroo Rat • Reduce Activity • Remain in Cool Burrow • Highly concentrated urine • Very dry feces (rectal absorption) • Metabolic water

  39. 39 Excretion of Nitrogeneous waste -When amino acids catabolized, amino group (-NH2) is released (deamination) -If not reused, need to excrete because toxic -Three main ways to dispose: 1-ammonia (most toxic, requires lots water) ‘ammonotelic’ (NH3) 2-urea (need 10% of water of NH3, but costs ATP) ‘ureotelic’ (2N) 3-uric acid (white pasty substance, low solubility, need 1% water as NH3) ‘uricotelic’ (4N) -Disposal depends on water availability 

  40. 40 Excretion of Nitrogeneous waste Knut Schmidt_Nielsen 1997

  41. 41 Knut Schmidt_Nielsen 1997

  42. 42 Excretion of Nitrogeneous waste -ammonia converted to non-toxic glutamine in the body for transport -ammonia toxic because -increases pH, -competes with K+ for ion transport, -alters synaptic transmission (14-31)

  43. 43 Osmoregulatory Mechanisms Apical surface (faces lumen and outside world) Basal surface (faces body and extracellular fluid) - Active movement of ions/salts requires ATP - Movement of water follows movement of ions/salts (14-11)

  44. 44 END

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