Respiratory pigmentsCO transfer at tissueLecture 19, 04 Nov 2003Chapter 13, Respiration, Gas Exchange, Acid-Base BalanceVertebrate PhysiologyECOL 437University of ArizonaFall 2003instr: Kevin Boninet.a.: Bret Pasch1Vertebrate Physiology 4371. Blood-Gas Chemistry (CH13)2. Announcements...2VOTE!Term Paper Draft due Thursday 06 Nov.Turn in old, relevant, graded work.On the actual most recent draft use aCODE NAME so your paper can beanonymously reviewed by one of yourpeers.We will give you a paper to edit/review atthe end of class on Thursday3Name that student:4Jane DavisHematologyOncologyFrenchKatie CoxTallKim HurdAir Force ROTCKnut Schmidt_Nielsen 1997Gravityand BP5Knut Schmidt_Nielsen 1997ExerciseOxygenConsumptionX 20Cardiac Output 6x6Chapter 13 – Blood-Gas ChemistryOxygen and Carbon Dioxide- Air vs. Water- Epithelial Transfer- Transport and RegulationpH regulationChloride shiftCarbonic AnhydraseElevationSkip: Diving, Swimbladder, Exercise7Gas composition in air O CO N% of dry air 21 0.03 78pp at 760 mm Hg 159 0.23 594380mmHg (at 6000m) 79.6 0.11 297Solubility in water (ml/L) 34 1,019 172228Why is pO2 in lungs less than ‘expected’?Effects of Temp and Solutes on O solubility2Temp (C) Fresh Sea 0 10.29 7.97 10 8.02 6.60 20 6.57 5.31Increase in temp Increase [ion]decrease solubility9Rate of diffusion depends on molecular weight (Graham’s Law) Air WaterO solubility >O rate of diffusion >Weight of medium <Movement of medium tidal unidirectional(amt. needed to get O )(take in,expel)(less energyrequired)22210Gas transfer1. Breathing (supply air or water to respiratorysurface)2. Diffusion of O & CO across resp. epithelium3. Bulk transport of gases by blood4. Diffusion across capillary walls (bloodmitochondria)2211(humans = 50-1002 m SA)13-112Respiratory 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/ Ocontent• ability to bind to O (affinity) affects carryingcapacity of blood for O2+ 2+2298% of O transported via carriermoleculesGas transport in blood222213hemoglobin hemocyanin hemerythrinMetal Fe Cu FeDistribution over 10 phyla 2 phyla 4 phyla (all verts, many inverts) (arthropods, mollusks)Location RBCs (verts) dissolved in intracellular plasmaColor deox – maroon colorless colorless ox – red blue reddish violet2+ 2+ 2+14Knut Schmidt_Nielsen 1997Hemoglobinand otherRespiratoryPigments15hememoleculeshemoglobin4 heme + 4 protein chainscan carry 4 O216hemoglobinFetal hemoglobin:γ chains (not β) w/ higher affinity for O(enhance O transfer from mother to fetus)Affinity for CO = 200 x’s greater than for OCO poisoning even at low partial pressuresAntarctic icefish lack pigmentlow metabolic needs = low metabolism high cardiac output, blood volumelarge heart22217O dissociation curvehyperbolicsigmoidal• not need lots of O to get near 100%Cooperativity-binding of 1st O2 facilitates more binding-oxygenation of 1st heme group increases affinity of remaining 3 for O22218Pigment w/ High P :50• low affinity• high rate of O transfer to tissuesPigment w/ Low P :P - pp of O at which pigment is 50% saturated50 2250• high affinity• high rate of O uptake219Factors that reduce affinity1. low pH (increase [H+])2. increase in CO23. elevated Temp4. organic compounds201. and 2. Increase in [CO ] or [H+]Factors that reduce affinity• Bohr effect CO and H bind to hemoglobin (allosteric site), whichchanges conformation of molecule andchanges binding site for Oat tissues:CO binds to hemoglobin, decreasing affinityfor O , allowing better delivery of O• Root effectfishes… (skip)222222+21Bohr EffectCO + H O H CO H + HCO22 23+3-Inc in Pco inc [H+] dec pH reduces affinity2CO enters blood at tissueshemoglobin unloads OCO leaves blood at resp. surfacehemoglobin uptake O2222Carbonic acidBicarbonate22Knut Schmidt_Nielsen 1997Bohr shiftas afunction ofbody size(small animals withgreater Bohr shift[more acid sensitive]so can more readilyleave oxygen attissues at given PO)23Factors that reduce affinity4. organic compounds• organophosphates in erythrocytes differ among spp.mammals: 2,3 DPGbirds: IPfish: ATP, GTP• bind to hemoglobin as allosteric effectors• used to maintain O affinity under hypoxic conditionsat high altitude (low blood [O ]) increase 2,3 DPGto increase delivery of O to tissues222324CO transport in blood2CO + H O H CO H + HCO CO + OH HCOProportions of CO , HCO depend on pH, T, ionic strength of bloodAt normal pH, Temp:80% of CO in form of bicarbonate ion HCO5-10% dissolved in blood10% in form of carbamino groups(bound to amino groups of hemoglobin)22 2233+-2--3-23-325Haldane effect• deox hemo has high affinity for H creating inc. [HCO ] inblood (more CO )•recall equations on previousslide+3-226Bohr effect + Haldane effectincreasing [CO2 ] decreases affinity ofhemoglobin for O2 , so binds CO2 more easily27CO transfer at tissue• enters/leaves blood as CO (more rapid diffusion)• passes thru RBCs• CO produced = O released no change in pHonly inRBC, notplasmamaintaincharge balancepassiveexchange,bidirectionaloxygenationof hemo:acidifyinterior(release H )deox of hemo:inc pH (bind H )Band IIIprotein222++2-Chloride Shift-Carbonic Anhydrase28CO transfer at lungdec. in HCO inRBC: influxfacilitateddiffusionAcidify RBC:facilitateHCO CO223-3-29Acid-Base balancing• Animal body pH: slightly alkaline (more OH than H )• maintain pH for stability of proteins (and function)H production / excretion• produced: metabolism of ingested foodingest meat: acid ingest plants: base• excreted continually via kidneys, gills, skin• build-up of CO build-up of H (acidify body)• low CO low H (alkaline body)small overall effecton pH+-2+2+30+pH buffers in blood:bicarbonate – not true buffer, but CO / HCO ratio imp. to pHexcretory organs (kidneys, gills, skin)proteins (hemoglobin), phosphatesCO + H O H CO H + HCORespiration and pH• inc. lung ventilation (low body [CO ])