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Dr. William R. Law Room 203A, CMW 6-7622 wrlaw@uic

Dr. William R. Law Room 203A, CMW 6-7622 wrlaw@uic.edu. http://www.uic.edu. /~wrlaw. Gas Laws to Remember. Dalton’s Law: Each gas in a mixture of gases exerts a pressure commensurate with its own concentration (partial pressures) Oxygen is 21% of air (FIO 2 = 0.21)

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Dr. William R. Law Room 203A, CMW 6-7622 wrlaw@uic

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  1. Dr. William R. Law Room 203A, CMW 6-7622 wrlaw@uic.edu http://www.uic.edu /~wrlaw

  2. Gas Laws to Remember • Dalton’s Law:Each gas in a mixture of gases exerts a pressure commensurate with its own concentration (partial pressures) • Oxygen is 21% of air (FIO2 = 0.21) At 760 torr, the PO2=0.21 X 760=160 *Adjustmant for P H20: 47 mmHg

  3. 100 80 47 mmHg 60 Vapor Pressure of Water (mmHg) 40 37oC 20 0 0 10 20 30 40 50 Temperature (oC)

  4. Gas Laws to Remember • Dalton’s Law:Each gas in a mixture of gases exerts a pressure commensurate with its own concentration (partial pressures) • Oxygen is 21% of air (FIO2 = 0.21) At 760 torr, the PO2=0.21 X 760=160 *Adjustmant for P H20: 47 mmHg At 760 Torr, PO2 = (760-47) X 0.21 = 150

  5. Gas Laws to Remember • Dalton’s Law:Each gas in a mixture of gases exerts a pressure commensurate with its own concentration (partial pressures) • Oxygen is 21% of air (FIO2 = 0.21) At 760 torr, the PO2=0.21 X 760=160 *Adjustmant for P H20: 47 mmHg • Henry’s Law: The volume of gas “x” dissolved in a liquid is proportionally and directly dependent upon its • Partial Pressure (surrounding the gas) • Fraction in mixture (%) • Total pressure of the mix (atmospheric; altitude; deep sea diving) • Solubility in the liquid (CO2 is ~20X more soluble than O2) • CX=KCPX

  6. PO2=100 mmHg PO2=100 mmHg

  7. For DiffusionFactors influencing volume of gas transferred per unit time • Trans-membrane partial pressure gradient NOT CONTENT! Gradient affected by • alveolar minute ventilation (Vdot) • pulmonary capillary flow (Qdot) • chemical reactions (Ex: Hb) Example: At the pulmonary arterial side of capillaries: PCO2 gradient is ~5-6 Torr PO2 gradient is ~40-50 Torr

  8. Hemoglobin Oxygen Transport • Characteristics • 4 Heme units(iron-containing porphyrin ring) 4 globin units(protein chains; thallassemias and “sickle cell” anemia due to mutations in these globins) • Combines reversibly with oxygen Oxyhemoglobin Deoxyhemoglobin * Methemoglobin: oxidized Hb wherein iron is oxidized (ferrous [Fe+2] to ferric state [Fe+3])

  9. PO2=100 mmHg PO2=100 mmHg Due to the presence of hemoglobin, the volume rate transfer of oxygen from the alveoli to the blood is increased.

  10. 0.003 ml O2 / dl blood mmHg Hemoglobin Oxygen Transport • Oxygen Capacity/Content • HB: Normal blood = 15 g/dl [100 ml] X 1.36 ml O2 / g Hb CAPACITY = ~20 ml O2 / dl blood (20 vol %) • Dissolved in Plasma : At PO2 100 mmHg = 0.3 vol% At PO2 760 mmHg = 2.3 vol%

  11. Hemoglobin Oxygen Transport • Characteristics • 4 Heme units(iron-containing porphyrin ring) 4 globin units(protein chains; thallassemias and “sickle cell” anemia due to mutations in these globins) • Combines reversibly with oxygen Oxyhemoglobin Deoxyhemoglobin * Methemoglobin: oxidized Hb wherein iron is oxidized (ferrous [Fe+2] to ferric state [Fe+3]) • Demonstrates cooperativity:the binding of oxygen to one site increases the affinity of other sites

  12. Total O 2 22 100 18 80 O combined 2 with Hb 14 60 O2 Content (ml O2/dl blood) Hb Saturation (%) 10 40 6 20 Dissolved O2 2 0 20 40 60 80 600 100 P (mmHg) O 2 Oxygen Transport

  13. Oxygen Transport 22 100 18 80 14 60 O2 Content (ml O2/dl blood) Hb Saturation (%) 10 40 6 20 2 0 20 40 60 80 600 100 P (mmHg) O 2 ΔPO2  ΔSaO2

  14. 20 )PO2 Same decrease 10 )PO2 in O2 content 0 200 300 400 100 Oxygen Transport O2 Content (ml/dl blood) PO2 (mmHg)

  15. 100 80 60 Hb Saturation (%) 40 20 0 20 40 60 80 100 P (mmHg) O 2

  16. Characteristics 4 Heme units(iron-containing porphyrin ring) 4 globin units(protein chains; thallassemias and “sickle cell” anemia due to mutations in these globins) Combines reversibly with oxygen Oxyhemoglobin Deoxyhemoglobin * Methemoglobin: oxidized Hb wherein iron is oxidized (ferrous [Fe+2] to ferric state [Fe+3] Demonstrates cooperativity:the binding of oxygen to one site increases the affinity of other sites Oxygen content is linearly related to saturation of Hb with oxygen Neither content nor saturation are linearly related to PO2 Hemoglobin Oxygen Transport

  17. vol%) 20 18 OR OR 16 14 /100 ml blood 12 10 2 8 6 Content (ml O 4 2 0 2 O 0 20 40 60 80 100 % Hb Saturation Anemia (Hb~10 g/dl) SHAM Anemia (Hb~7.5 g/dl)

  18. 22 100 anemia 18 80 14 60 O2 Content (ml O2/dl blood) 10 40 6 20 2 0 20 40 60 80 100 P (mmHg) O 2 Oxygen Transport S.H.A.M. Hb Saturation (%) SaO2  CaO2 anemia

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