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

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Presentation on theme: "Dr. William R. Law Room 203A, CMW 6-7622"— Presentation transcript:

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2 Dr. William R. Law Room 203A, CMW

3 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) At 760 torr, the PO 2 =0.21 X 760=160 *Adjustmant for P H 2 0: 47 mmHg Gas Laws to Remember

4 Temperature ( o C) Vapor Pressure of Water (mmHg) 37 o C 47 mmHg

5 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) At 760 torr, the PO 2 =0.21 X 760=160 *Adjustmant for P H 2 0: 47 mmHg Gas Laws to Remember At 760 Torr, PO 2 = (760-47) X 0.21 = 150

6 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) At 760 torr, the PO 2 =0.21 X 760=160 *Adjustmant for P H 2 0: 47 mmHg Gas Laws to Remember 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 (CO 2 is ~20X more soluble than O 2 ) C X =K C P X

7 PO 2 =100 mmHg

8 For Diffusion Factors 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: PCO 2 gradient is ~5-6 Torr PO 2 gradient is ~40-50 Torr

9 Hemoglobin 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 OxyhemoglobinDeoxyhemoglobin * Methemoglobin: oxidized Hb wherein iron is oxidized (ferrous [Fe +2 ] to ferric state [Fe +3 ]) Oxygen Transport

10 PO 2 =100 mmHg Due to the presence of hemoglobin, the volume rate transfer of oxygen from the alveoli to the blood is increased.

11 Hemoglobin Oxygen Capacity/Content HB: Normal blood = 15 g/dl [100 ml] X 1.36 ml O 2 / g Hb CAPACITY = ~20 ml O 2 / dl blood (20 vol %) Dissolved in Plasma : Oxygen Transport ml O 2 / dl blood mmHg At PO mmHg = 0.3 vol% At PO mmHg = 2.3 vol%

12 Hemoglobin 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 OxyhemoglobinDeoxyhemoglobin * Methemoglobin: oxidized Hb wherein iron is oxidized (ferrous [Fe +2 ] to ferric state [Fe +3 ]) Oxygen Transport Demonstrates cooperativity: the binding of oxygen to one site increases the affinity of other sites

13 Hb Saturation (%) P O (mmHg) O 2 combined with Hb O 2 Content (ml O 2 /dl blood) Dissolved O 2 Total O 2 Oxygen Transport

14 Hb Saturation (%) P O (mmHg) O 2 Content (ml O 2 /dl blood) Oxygen Transport ΔPO 2  ΔSaO 2

15 O 2 Content (ml/dl blood) PO 2 (mmHg) ) PO 2 Same decrease in O 2 content ) PO 2 Oxygen Transport

16 Hb Saturation (%) P O 2 (mmHg)

17 Hemoglobin 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 OxyhemoglobinDeoxyhemoglobin * 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 Transport Oxygen content is linearly related to saturation of Hb with oxygen Neither content nor saturation are linearly related to PO 2

18 % Hb Saturation O 2 Content (ml O 2 /100 ml blood OR vol%) SHAM Anemia (Hb~7.5 g/dl) Anemia (Hb~10 g/dl)

19 Hb Saturation (%) P O (mmHg) O 2 Content (ml O 2 /dl blood) Oxygen Transport SaO 2  CaO 2 S.H.A.M. anemia


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