1 / 16

Gas Transport

Gas Transport. Prof. K. Sivapalan. Transport of gases in Blood. Reaction of Oxygen with Haemoglobin. Iron atoms in Hb bind reversibly with O 2 - Oxygination . 4Hb + 4O 2 ↔ Hb 4 O 8 Oxygen dissociation curve illustrates the relation of PO 2 to saturation.

nigel
Download Presentation

Gas Transport

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Gas Transport Prof. K. Sivapalan

  2. Transport of gases in Blood Gas Transport

  3. Reaction of Oxygen with Haemoglobin • Iron atoms in Hb bind reversibly with O2- Oxygination. • 4Hb + 4O2↔ Hb4O8 • Oxygen dissociation curve illustrates the relation of PO2 to saturation. • The sigmoid curve is the result of changing affinity of Hb to oxygen. • When fully saturated, 1 g Hb carries 1.34 ml oxygen Gas Transport

  4. Factors Affecting the Affinity of Haemoglobin to Oxygen • Factors that reduce the affinity [shift the curve to right, increase P50] • Rise in temperature • Fall in pH • Rise in 2,3-biphosphoglycerate • P50- partial pressure at which 50 % haemoglogin is saturated. Gas Transport

  5. Reaction with CO • Carbon monoxide reacts with haemoglobin in the same way as oxygen but the affinity is 250 times more. Gas Transport

  6. 2,3- Biphosphoglycerate • It binds to β chain of deoxyhaemoglobin • Alkalinity, thyroid hormone, androgens and growth hormone increase it. • Exercise causes increase in 60 minutes but it may not occur in trained athlets. Gas Transport

  7. Color Changes of Haemoglobin • Haemoglobin is blue • Oxyhaemoglobin is pink • Cyanisis- blue discolorizationduetodeoxigination. • It becomes apperant if deoxyhaemoglobin is more than 5g/dl • Carboxyhaemoglobin is cherry red Gas Transport

  8. Transport of Carbon Dioxide • Considerable amount of CO2 remains dissolved in plasma. • CO2 enters red cells and carbonic anhydrase catalyses formation of Hydrogen and bicarbonate. • CO2 reacts with NH2 in proteins [haemoglobin and plasma proteins] to form carbamino compound. Gas Transport

  9. Bicarbonate Formation and Chloride Shift • The dissociation of carbonic acid formed in red cells as H+ and HCO3- will not proceed unless at least one is removed. • The Hb is a good buffer and takes up H+ and the reaction continues. • The resulted HCO3- concentration rises and difuses into plasma. • The electrical in-equilibrium drags Cl- into red cell. • This increases osmolality and the red cell volume increases. • 70 % of the CO2 is transported as HCO3- Gas Transport

  10. Summary of CO2 in DL blood Gas Transport

  11. Carbon Dioxide Dissociation Curve Gas Transport

  12. Interaction of Oxygen and Carbon Dioxide with Haemoglobin • Increase of CO2 promotes dissociation of O2- Bohr Effect. • Oxygination tends to displace CO2 from blood- Haldane effect. • Oxy haemoglobin is more acidic • Less tendancy to form carbamino compounds. • Less tendancy to accept hydrogen ion. Gas Transport

  13. Summary of Changes in Lungs • Oxygen up take- 250 ml/min. • Carbon dioxide output- 200 ml/min. • Respiratory exchange ratio- • CO2/O2 = 200/250 =0.8 • Oxygen uptake is facilitated by carbon dioxide dissociation and carbon dioxide dissociation is facilitated by oxygenation. Gas Transport

  14. Physiologic Shunt of Venous Blood • Drainage of small amounts of bronchial blood into pulmonary vein • Left ventricular blood draining into the chamber directly. • The result is blood in aorta with 95 % saturation of oxygen. Gas Transport

  15. Exchange in Tissues • The cells are using oxygen and the partial pressure is very low. • The cells are producing carbon dioxide and the partial pressure is high. • The gases diffuse according to the Partial pressure difference through the tissue fluid. • Higher temperature, higher PCO2, more acidity facilitate de-oxigenation and deoxigenation facilitates CO2 reaction with haemoglobin Gas Transport

  16. Supply of Oxygen • When tissue metabolism increases, the tissue partial pressure falls. • Slight fall in partial pressure results in dissociation of more oxygen from haemoglobin. • Myoglobin in muscles releases oxygen when the partial pressure is very low. Gas Transport

More Related