nd Lecture Fri 06 Mar 009 Vertebrate Physiology ECOL 437 (MCB/VetSci 437) Univ. of Arizona, spring 009 Kevin Bonine & Kevin Oh Oxygen, Carbon Dioxide Respiration Gas Transport Chapter 1-3 1 Housekeeping, Fri 06 March 009 Readings Today: Ch 1 (oxygen, carbon dioxide) Mon 09 Mar: Ch (respiration) Wed 11 Mar: Ch3 (gas transport) Fri 13 Mar: Second Midterm 14- March Spring Break Fri 13 Feb = Exam 1 Lab discussion leaders: xx 1pm xx 3pm xx Lab discussion leaders: 5 Mar 1pm Sam 3pm Karri, Jason 1
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5 Gases Food Salts Water Waste (Temp) 6 3
Oxygen needed for cellular respiration Make ATP Hill et al., 004, Fig. 0.6 7 1% Oxygen in Air Hill et al., 004, Fig. 0.1 Partial Pressure = Total Pressure x Percent Composition 8 4
Partial Pressures Gas composition in air O CO N % of dry air 1 0.03 78 pp at 760 mm Hg sea level 159 0.3 594 380mmHg (at 6000m) 79.6 0.11 97 Solubility in water (ml/l) 34 1,019 17 9 Cold Air/Water holds More Oxygen Hill et al., 004 10 5
Oxygen Partial Pressure Decreases from Air to Mitochondria Why is po in lungs less than expected? Hill et al., 004, Fig. 0.5 11 Gas Transfer 1. Breathing (supply air or water to respiratory surface). Diffusion of O & CO across resp. epithelium 3. Bulk transport of gases by blood (humans = 50-100 m SA) 4. Diffusion across capillary walls (blood mitochondria) 1 6
1. Breathing. Diffusion 3. Bulk transport 4. Diffusion Mitochondria 13 Why did circulatory systems evolve? Fick s Law of Diffusion Q=kA P -P 1 D Q =rate of diffusion k =diffusion coefficient (varies) A =x-sectional area for diffusion P -P 1 = pressure gradient D = distance to diffuse across 14 7
Fick Equation Q=kA P -P 1 D Which of these will increase rate of diffusion of a gas like oxygen: A Increasing distance (D) across which gas must travel B Increasing P1 relative to P C Increase area (A) across which gas moves D Changing from air to water (~k) E Decreasing P relative to P1 15 Rate of Diffusion Air Water O solubility > O rate of diffusion > Weight of medium < (amt. needed to get O ) Movement of medium tidal unidirectional (take in, (less energy expel) required) 16 8
In flatworm, all cells are within 1mm of water No need for circulatory system 17 Hill et al., 004, Fig. 1.8 Some Gas Exchange Across Skin 18 9
Lake Titicaca Frog (Bolivian Navy; Peru-Bolivia border) 19 Knut Schmidt_Nielsen 1997 Circulatory System allowed Animals to get BIGGER Hill et al., 004, Fig. 0.4 0 10
Hill et al., 004, Fig. 1.1 1 Membranes and Fluids are Gas Diffusion Barriers: Why can pneumonia kill you? (Eckert, 13-) 11
Hill et al., 004, Fig. 0.4 3 Mammalian Ventilation -lungs are elastic bags -suspended in pleural cavity within thoracic cage (ribs and diaphragm define, fluid lines) -low volume pleural space between lung and thoracic wall -negative pressure to inflate lungs (increase volume) -pneumothorax 4 1
Mammalian Ventilation (Eckert, 13-8) -negative pressure to inflate lungs (increase volume) 5 Mammalian Ventilation -expiration usually passive (Eckert, 13-30) 6 13
Frog Ventilation -Positive pressure 1. Into mouth (buccal cavity). Close nares, open glottis and force air into lungs by raising buccal floor (Eckert, 7 13-33) Mammalian Lung Alveoli and Capillaries RBC (not to scale) 8 Knut Schmidt_Nielsen 1997 14
Lung Anatomy (Eckert, 13-1) Nonrespiratory -Trachea -> -Bronchi -> -Bronchioles -> Respiratory -Terminal bronchioles -> -Respiratory bronchioles -> -Alveoli -Cilia and Mucus 9 Lung Ventilation -Small mammals with greater per gram O needs and therefore greater per gram respiratory surface area? -Dead Space (anatomic and physiological) Swan (Eckert, 13-4) 30 15
Lung Ventilation (Eckert, 13-3) 31 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 3 16
Panting Dogs? 33 Knut Schmidt_Nielsen 197 Rate and Depth Regulation -Primarily via CO changes (central) -Peripheral Chemoreceptors PO, PCO, ph (Vagus nerve to medulla oblongata) -Innervate Medullary Respiratory Center (phrenic nerve to diaphragm and intercostals) (Eckert, 13-46) -Emotions, sleep, light, temperature, speech, volition, etc. O ~controls respiration in aquatic vertebrates, Why? 34 17
Rate and Depth Regulation (Eckert, 13-48) Long term -Central Chemoreceptors 35 To Diaphragm alveolar (Eckert, 13-45) 36 18
Hering-Breuer reflex -Stimulation of stretch receptors inhibits medullary inspiratory center -Prevent overinflation -Ectotherms often breathe intermittently 37 1 1 (Eckert, 13-45) To Diaphragm 38 19
Bird Lung Ventilation Unidirectional!! 39 Knut Schmidt_Nielsen 1997 Bird Ventilation -lung volume changes very little, air sacs instead (Eckert,13-3) (Eckert,13-3) Unidirectional 40 0
Knut Schmidt_Nielsen 197 Mammal Lung Alveoli Bird Lung Parabronchi 41 Fish Gill 4 Knut Schmidt_Nielsen 1997 1
Fish Gills Hill et al., 004, Fig. 1.10 43 35 Fish Gill -breathing in water -need much higher ventilation rate -unidirectional -pump water across gills (or ram ventilation) Knut Schmidt_Nielsen 1997 44
Why aren t fish gills tidal? unidirectional tidal Hill et al., 004, Fig. 0.3 45 high Relative Gill Surface Area in Fishes low 46 Knut Schmidt_Nielsen 1997 3
Animals with higher oxygen needs increase diffusion area Hill et al., 004, Fig. 1.7 47 Animals with higher oxygen needs reduce diffusion distances Hill et al., 004, Fig. 1.7 48 4
Concurrent water How could you design a pair of vessels in the gill for more efficient exchange? Hill et al., 004, Fig. 1.4 49 Counter-Current Exchangers 50 5
Cross-current Hill et al., 004, Fig. 1.5 51 Vertebrate Gas Transport 5 6
Oxygen Transport Hill et al., 004, Fig. 1.4 Hill et al., 004, Fig. 1.3 53 Gas transport in blood Respiratory pigments + + all have either Fe or Cu ions that O binds pigment increases O content of blood complex of proteins and metallic ions each has characteristic color that changes w/ O content ability to bind to O (affinity) affects carrying capacity of blood for O 98% of O transported via carrier molecules 54 7
Hill et al., 004, Fig..4 55 hemoglobin hemocyanin hemerythrin + + + Metal Fe Cu Fe Distribution over 10 phyla phyla 4 phyla (all verts, many inverts) (arthropods, mollusks) Location RBCs (verts) dissolved in intracellular plasma Color deox maroon colorless colorless ox red blue reddish violet 56 8
Hemoglobin and other Respiratory Pigments 57 Knut Schmidt_Nielsen 1997 hemoglobin 4 heme + 4 protein chains 98% of O transported via carrier molecules can carry 4 O heme molecules 58 9
Hemoglobin Fun Facts: Fetal hemoglobin: gamma chains (not β) w/ higher affinity for O (enhance O transfer from mother to fetus) Affinity for CO = 00 x s greater than for O Antarctic icefish lack pigment -low metabolic needs = low metabolism -high cardiac output, blood volume -large heart 59 Oxygen dissociation curve Hyperbolic (myoglobin) Sigmoidal (Hemoglobin) -rate of binding changes Hemoglobin Cooperativity: -binding of 1st O facilitates more binding -oxygenation of 1st heme group increases affinity of other 3 for O 60 30
Steep Part of Oxygen Dissociation Curve, Quickly Unload Oxygen 61 Hill et al., 004, Fig..6 UNLOAD MORE oxygen when tissues NEED MORE Why does partial pressure of oxygen in tissues decrease with exercise? Hill et al., 004, Fig..5 6 31
Hill et al., 004, Fig..7 Sigmoidal vs. Hyperbolic 63 Factors that reduce affinity 1. low ph (increase [H+]). increase in CO 3. elevated Temp 4. organic compounds 64 3
Factors that reduce affinity 1. and. Increase in [CO ] or [H+] Bohr effect CO and H + bind to hemoglobin (allosteric site), which changes conformation of molecule and changes binding site for O at tissues: CO binds to hemoglobin, decreasing affinity for O, allowing better delivery of O 65 Bohr Effect CO enters blood at tissues hemoglobin unloads O CO leaves blood at resp. surface hemoglobin uptake O CO + H O H CO H + + HCO - 3 3 Carbonic acid Bicarbonate Inc in Pco inc [H+] dec ph reduces affinity 66 33
Bohr Effect Hill et al., 004, Fig..11 67 Bohr shift as a function of body size (small animals with greater Bohr shift [more acid sensitive] so can more readily leave oxygen at tissues at given PO) 68 Knut Schmidt_Nielsen 1997 34
Factors that reduce affinity 4. organic compounds organophosphates in erythrocytes differ among spp. mammals:,3 DPG birds: IP 3 fish: ATP, GTP bind to hemoglobin as allosteric effectors used to maintain O affinity under hypoxic conditions at high altitude (low blood [O ]) to increase delivery of O to tissues? increase,3 DPG 69 Carbon Dioxide Transport 70 35
Hill et al., 004, Fig..0 71 Hill et al., 004, Fig..1 7 36
CO transport in blood carbonic acid bicarbonate CO + H O H CO 3 H + + HCO - 3 HCO - 3 H + + CO - 3 carbonate CO + OH - HCO - 3 Proportions of CO, HCO - 3 depend on ph, T, ionic strength of blood At normal ph, Temp: 80% of CO in form of bicarbonate ion HCO - 3 5-10% dissolved in blood 10% in form of carbamino groups (bound to amino groups of hemoglobin) 73 Haldane effect deox hemo has high affinity for H + creating inc. [HCO - 3 ] in blood (more CO ) recall equations on previous slide 74 37
Carbon Dioxide Transport: Hill et al., 004, Fig.. 75 CO transfer at tissue enters/leaves blood as CO (more rapid diffusion) passes thru RBCs CO produced = O released no change in ph -Chloride Shift -Carbonic Anhydrase oxygenation of hemo: acidify interior (release H + ) Band III protein only in RBC, not plasma maintain charge balance (13-10) deox of hemo: increase ph (bind H + ) 76 38
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