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

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

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

50 100 010203040 Temperature ( o C) 0 20 40 60 80 Vapor Pressure of Water (mmHg) 37 o C 47 mmHg

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

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

PO 2 =100 mmHg

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

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

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

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 0.003 ml O 2 / dl blood mmHg At PO 2 100 mmHg = 0.3 vol% At PO 2 760 mmHg = 2.3 vol%

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

Hb Saturation (%) 100 80 60 40 20 0 2 406080 100 600 P O (mmHg) O 2 combined with Hb O 2 Content (ml O 2 /dl blood) 2 6 10 14 18 22 Dissolved O 2 Total O 2 Oxygen Transport

Hb Saturation (%) 100 80 60 40 20 0 2 406080 100 600 P O (mmHg) O 2 Content (ml O 2 /dl blood) 2 6 10 14 18 22 Oxygen Transport ΔPO 2  ΔSaO 2

O 2 Content (ml/dl blood) 20 10 0 PO 2 (mmHg) 100 200300400 ) PO 2 Same decrease in O 2 content ) PO 2 Oxygen Transport

Hb Saturation (%) 100 80 60 40 20 0 406080 100 P O 2 (mmHg)

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

020406080100 % Hb Saturation 0 2 4 6 8 10 12 14 16 18 20 O 2 Content (ml O 2 /100 ml blood OR vol%) SHAM Anemia (Hb~7.5 g/dl) Anemia (Hb~10 g/dl)

Hb Saturation (%) 100 80 60 40 20 0 2 406080 100 P O (mmHg) O 2 Content (ml O 2 /dl blood) 2 6 10 14 18 22 Oxygen Transport SaO 2  CaO 2 S.H.A.M. anemia