Dr. Puntarica Suwanprathes. Version 2007

Transcription

1 Dr. Puntarica Suwanprathes Version 2007

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3 O 2 and CO 2 transport in blood Oxyhemoglobin dissociation curve O 2 consumption (VO 2 ) CO 2 production (VCO 2 )

4 O 2 capacity O 2 content: CaO 2 or CvO 2 %saturation of Hb with O 2 : %SaO 2 O 2 delivery: DaO 2 O 2 extract

5 CaO 2 PaO 2 O 2 capacity CvO 2 %SaO 2 VCO 2 VO2 2 DaO 2 Q CaO 2

6 1. Dissolved in plasma dissolved O 2 2. Combination with Hemoglobin Oxyhemoglobin

7 Dissolved in plasma 3% Henry s law volume α partial pressure of that gas of dissolved gas blood 100 ml PO 2 1 mmhg dissolved O ml Po 2 in arterial blood = 100 mmhg dissolved O 2 = 0.3 ml / 100 ml.blood

8 dissolved O 2 = 0.3 ml/ 100 ml.blood O 2 consumption (at rest) = 250 ml/min If use only dissolved O 2..? cardiac output = 250 x 100 ml/min = 83.3 L/min 0.3 BUT cardiac output (at rest) = 5-6 L/min

9 Combination with Hemoglobin 97% O 2 Hemoglobin (Hb) Oxyhemoglobin Hb + O 2 HbO 2 reversible reaction total O 2 carrying capacity times

10 Hemoglobin 4 polypeptide chains or subunit Globin protein Heme (iron-porphyrin compound) conjugated protein 1Hbmolecule = 4 subunits Heme O 2

11 saturation Hemoglobin Hb + O 2 HbO 2 reversible reaction deoxyhemoglobin (reduced Hb) oxyhemoglobin Hb 4 +4O 2 Hb 4 O 8 oxygenation (0.01 sec.)

12 purple-red deoxygenated hemoglobin of the venous blood bright-red oxyhemoglobin of the arterial blood Hb + O 2 Hemoglobin acid warm low O 2 high CO 2 neutral cool high O 2 low CO 2 Hb(O 2 ) 4 oxyhemoglobin oxyhemoglobin gives up its oxygen

13 in the capillaries of the lungs lower temperature higher ph oxygen pressure

14 Gas transportation in blood dissolved O 2 /CO 2 exert pressure Binding O 2 /CO 2 (chemical reaction)

15 Oxygen capacity Oxygen content % hemoglobin saturation Oxygen delivery Oxygen consumption

16 Oxygen content Oxygen capacity % hemoglobin saturation oxygen content = dissolved O 2 + oxyhemoglobin oxyhemoglobin = oxygen content - dissolved O 2 %saturation of Hb = O 2 combine with Hb with O 2 O 2 capacity of Hb (or %SaO 2 ) X 100

17 oxygen content = dissolved O 2 + oxyhemoglobin oxyhemoglobin = oxygen content - dissolved O 2 %saturation of Hb = O 2 combine with Hb with O 2 O 2 capacity of Hb (or %SaO 2 ) X 100 (oxyhemoglobin) O 2 combine with Hb = %saturation of Hb x O 2 capacity of Hb 100

18 size? Htc.? p.560

19 Oxygen capacity of Hb In normal: Hb 15 gm/ 100ml. blood 15gm% Hb 1 gm O ml (max.) Oxygen capacity = O 2 (max.) combine with Hb in 100ml. blood = 15 x 1.34 = 20.1 ml in 100ml. blood O ml ~ 20 vol%

20 CaO 2 Oxygen content O 2 content = totalo 2 in blood (arterial blood) = dissolved O 2 + oxyhemoglobin 0.3 ml ml 19.8 ml ~ 20 ml = (PO 2 x 0.003) + [(O 2 capacity)x %SaO 2 ] / mmhg A-V shunt = 1.34 x 15 = 20.1 ml 97% of (20.1 ml) = 19.5 ml 100% saturation 97% saturation

21 CvO 2 Oxygen content O 2 content = totalo 2 in blood (venous blood) = dissolved O 2 + oxyhemoglobin = (PO 2 x 0.003) + [( O 2 capacity) x %SvO 2 ]/ mmhg O 2 combine with Hb = % saturation = % of (20.1 ml) = ml = ml = 15 ml

22 DO 2 Oxygen delivery O 2 content = total O 2 in blood (arterial blood) ~ 20 ml (in 100 ml. blood) Q = 5 L/min cells DO 2 Q x CaO 2 (x10) (unit: ml/min)

23 Oxygen delivery venous blood O 2 15 ml in 100ml. blood arterial blood O 2 20 ml in 100ml. blood

24 Venous blood PO 2 = 40 mmhg in 100ml. blood Arterial blood PO 2 = 100 mmhg dissolved O 2 = ml = 0.12 ml Oxyhemoglobin = ml ~ 15 ml dissolved O 2 = ml = 0.3 ml Oxyhemoglobin = 19.5 ml ~ 20 ml ~ 5 ml or 250 ml/min (if C.O. = 5000 ml/min) O 2

25 VO 2 Oxygen consumption in 100ml. blood oxygen content Arterial blood ~ 20 ml Venous blood ~ 15 ml cells ~ 5 ml

26 O 2 content in 100ml. blood Arterial blood ~ 20 ml Venous blood ~ 15 ml in 100ml. blood cells ~ 5 ml cells use ~ 5 ml VO 2 Q = 5 L/min C.O. = 5000 ml/min 5000 x 5 ml 100 = 250 ml Oxygen consumption

27 VO ml/min Oxygen consumption

28 Oxyhemoglobin dissociation curve dissociation separation O 2 dissociation release O 2 from HbO 2 Hb + O 2 HbO 2 reversible reaction %SaO 2

29 Arterial blood Venous blood Oxyhemoglobin dissociation curve v a 50% SaO 2 %SaO 2 p.563

30 Oxyhemoglobin dissociation curve a v unloading loading associated part or flat part dissociated part or steep part %SaO 2

31 Factors affecting O 2 dissociation curve 1. PCO 2 2. H + concentration 3. temperature 4. 2,3 diaphsphoglyceric acid (2,3 DPG) in RBC ( β chain of oxyhemoglobin)

32 Factors O 2 affinity to Hb release O 2 Shift to left Factors Shift to right O 2 affinity to Hb release O 2 PCO 2 ph Bohr effect

33 P50 Normal o C, ph 7.4 PCO 2 40 mmhg Shift to right P50 O 2 affinity to Hb ***

34 Effect of 2,3 diphosphoglyceric acid (2,3 DPG) 2,3 DPG RBC HbO 2 + 2,3 DPG Hb-2,3 DPG + O 2 2,3 DPG HbO 2 release O 2 shift to right = O 2 affinity to Hb hypoxia (>2-3 hrs) 2,3 DPG anemia blood (in Blood bank) hypoxemia chronic lung diseases exercise

35 1. Dissolved in plasma dissolved CO 2 (6%) 2. Diffuse to RBC dissolved CO 2 in intracellular fluid react with NH 2 -group carbaminohemogloblin react with H 2 O bicarbonate

36 Dissolved in plasma Henry s law volume α of dissolved gas dissolved CO 2 (6%) partial pressure of that gas solubility-20 times : CO 2 > O 2 in blood 100 ml: PCO 2 1 mmhg 20x(0.003) = 0.06 dissolved CO ml

37 react with H 2 O bicarbonate in plasma (88%)*** in RBC *** (500 times faster) in RBC in plasma slow CA CO 2 + H 2 O H 2 CO 3 H + + HCO 3 Carbonic acid Bicarbonate CA: carbonic anhydrase

38 react with NH 2 - (amino group) carbaminohemogloblin (6%) in plasma in plasma in RBC CO 2 +R-NH 2 RNHCOOH RNHCOO + H + plasma protein in RBC protein part in Hb carbamino compounds CO 2 + HbO 2 carbamino hemoglobin + O 2 HbCO 2

39 Venous blood PCO 2 = 46 mmhg dissolved CO 2 = 46 x 0.06 ml = 2.7 ml Bicarbonate carbaminohb = 50.3 ml ~ 53 ml ~ 4 ml or ml/min (if C.O. = ml/min) average 210 ml/min in 100ml. blood CO 2 Arterial blood PCO 2 = 40 mmhg dissolved CO 2 = 40 x 0.06 ml = 2.4 ml Bicarbonate = 43.8 ml carbaminohb = 2.6 ml ~ 49 ml

40 VCO 2 Carbon dioxide production Carbondioxide content in 100ml. blood Arterial blood Venous blood ~ 49 ml ~ 53 ml cells ~ 4 ml

41 in 100ml. blood Carbondioxide content Arterial blood ~ 49 ml Venous blood ~ 53 ml VCO 2 cells ~ 4 ml in 100ml. blood cells release ~ 4 ml C.O. = 5000 ml/min 5000 x 4 ml 100 = 200 ml Carbondioxide production

42 VCO ml/min carbon dioxide production

43 tissue capillary CO 2 dissolved CO 2 CO 2 +R-NH 2 RNHCOOH RNHCOO + H + *** O 2 dissolved CO 2 CO 2 + H 2 O H 2 CO 3 H + + HCO 3 plasma CO 2 pulm. capillary oxygenation p.568 (HbCO 2 ) CO 2 + HbO 2 carbaminohb + O 2 CO 2 + H 2 O H 2 CO 3 RBC H 2 O Cl - Chloride shift CA HCO 3 + H + H + + HbO 2 buffered H + Hb - + O Peripheral blood 2 de-oxygenation higher ph affinity to CO 2 HHb= reduced Hb Haldane effect *** plasma

44 Haldane effect PO 2 carbaminohb: HbCO 2 release CO2 Oxygenation (@ lungs) ph HbCO 2 + O 2 HbO 2 + CO 2 affinity to CO 2 expired air

45 Carbon dioxide dissociation curve 53 vol% 49 vol% 4vol% arterial blood venous blood dissolved CO 2

46 more steep *** p.571

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