transport of carbon dioxide.pptx and haldane effect

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1. TRANSPORT OF CARBON DIOXIDE PRESENTOR:DR.VIDYA PANDA PGT 1 ST YEAR

2. INTRODUCTION CARBON DIOXIDE PRODUCTION,METABOLISM AND DIFFUSION CARBON DIOXIDE PRESSURE DIFFERENT FORMS IN WHICH CARBON DIOXIDE IS TRANSPORTED HALDANE EFFECT

3. HISTORY HJ Hamberger , he described the (often called "Hamburger shift), the process by which cells exchange bicarbonate for chloride ion. The effect of loading of oxygen in the lung facilitating unloading of carbon dioxide is named after him and popularly known as Haldane effect.

4. INTRODUCTION In the tissues, oxygen reacts with various food stuffs to form large quantities of C02. This Co2 enters the tissue capillaries and is transported back to the lungs. Co2 like oxygen, combines with the chemical substance (Hb), that increases the Co2 transport 15-20 folds. Under normal resting conditions, an average of 4 ml of carbon Dioxide is transported from tissues to the lungs in each 100 ml of blood.

5. CARBON DIOXIDE PRODUCTION,METABOLISM AND DIFFUSION When oxygen is used by the cells, all of it becomes CO2 and increases intra cellular PCO2 Due to pressure gradient, CO2 diffuses from cells into tissue capillaries In the lungs, it diffuses from pulmonary capillaries into the alveoli and expired Each point of the process, CO2 diffuses exactly opposite to the diffusion of O2 CO2 diffuses 20 times rapidly than O2. The pressure difference required for CO2 transport is very less when compared to O2

6. CARBON DIOXIDE PRESSURE Pulmonary capillary blood entering the lungs at arterial end has PCo2 of 45 mmHg Alveolar PCO2 is 40 mmHg Pulmonary capillary blood pCO2 becomes 40 mmHg before it has passed more than about one third distance through the capillaries

7. DISSOLVED STATE The amount of Co2 dissolved in the fluid of blood at 45 mmHg is about 2.7 mL/DL. The amount of Co2 dissolved in the fluid of blood at 40 mmHg is about 2.4 mL/DL. The difference is 0.3 mL. That is only 0.3 mL of Co2 is transported in dissolved form by each 100 ml of blood flow.

8. BICARBONATE ION The dissolved Co2 in the blood reacts with water to form carbonic acid This reaction occurs so rapidly in RBC (fraction of second) The protein required for this reaction is carbonic anhydrase (present in RBC) In another fraction of second, the carbonic acid formed in RBC, (H2Co3), dissociates into hydrogen and bicarbonate ions (H+ and HCO3-). This step occurs with out enzymes Most of the hydrogen ions combines with hemoglobin in the RBC (Hb is a powerful acid-base buffer)

9. CARBAMINO HAEMOGLOBIN FORM Transport of CO2 in combination with hemoglobin and plasma proteins CO2 reacts directly with amine radicals of hemoglobin molecule to form carbamino hemoglobin (CO2 Hgb) This does not require enzymes Reduced hemoglobin more readily form carbamino hemoglobin This combination is reversible so that the CO2 can be released into alveoli where PCO2 is lower than the pulmonary capillaries

10. Small amounts of CO2 also reacts in the same way with plasma proteins in the tissue capillaries This reaction is much less significant The quantity of the plasma proteins in the blood is only one-forth as great as the quantity of hemoglobin 30% of CO2 is transported in carbaminohemoglobin form 1.5 mL of Co2 is transported in carbaminohemoglobin form in 100 mL of blood

11. HALDANE EFFECT Favors CO2 unloading or loading by change in the pressures of oxygen Oxygen pressure changes help loading/ unloading of CO2 High oxygen pressure helps unloading of CO2 (lungs) Lower oxygen pressure helps loading of CO2 (tissues) Haldane effect is reverse of Bohr effect

12. When there is high PO2 (lungs =104 mmHg) Oxygen binds with hemoglobin Hemoglobin becomes more acidic Hemoglobin releases hydrogen ions Hydrogen ions reacts with bicarbonate ions Formation of H2CO3 Dissociation of H2CO3 into H2O and CO2 CO2 unloaded (enters alveoli)

13. HALDANE EFFECT At the level of tissues PCO2 is 45 mmHg PO2 is 40 mmHg Lower PO2 Favors loading of CO2 This causes 52 volumes % of CO2 to be loaded

14. HALDANE EFFECT At the level of lungs PCO2 is 45 mmHg PO2 is 40 mmHg (imagine no change in pO2) No Haldane effect This causes decrease in the % volumes of CO2 to 50 ( from 52 to 50) Only 2 volume % is unloaded with out Haldane effect

15. HALDANE EFFECT At the level of lungs PCO2 is 45 mmHg PO2 is 104 mmHg Higher PO2 Favors unloading The volume % of CO2 decreases to 48 (from 52 to 48) 4 volume % of CO2 is unloaded Haldane effect doubles the loading (tissues)/ unloading (lungs) of CO2

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