1 / 14

CO 2 Transport ~5 ml CO 2 / 100 ml systemic venous blood ~20% of CO 2 carried as carbamino-Hb

H. H. N. N. CO 2 Transport ~5 ml CO 2 / 100 ml systemic venous blood ~20% of CO 2 carried as carbamino-Hb (HbCO 2 ). H. COOH. Hb. HbCO 2. C.A. CO 2 + H 2 O. H 2 CO 3. HCO 3 - + H +. C.A. = Carbonic anhydrase found in virtually all phyla in human, in RBC.

reuel
Télécharger la présentation

CO 2 Transport ~5 ml CO 2 / 100 ml systemic venous blood ~20% of CO 2 carried as carbamino-Hb

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. H H N N CO2 Transport ~5 ml CO2/ 100 ml systemic venous blood ~20% of CO2 carried as carbamino-Hb (HbCO2) H COOH Hb HbCO2

  2. C.A. CO2 + H2O H2CO3 HCO3- + H+ • C.A. = Carbonic anhydrase • found in virtually all phyla • in human, in RBC ~80% of CO2 carried in solution in plasma as HCO3- fast SLOW! Blood is in tissue capillaries for only 5 seconds!

  3. Choride shift - must maintain same number of positive and negative charges in cell. HCO3- / Cl- exchanger When HCO3- moves out, Cl- moves in. Reverse chloride shift - HCO3- / Cl- exchanger moves Cl- out of RBC and HCO3-in.

  4. Central Regulation of Ventilation • Examine neural control of breathing • Respiratory centers in the brain • Peripheral input to respirator centers

  5. Peripheral Input to Respiratory Centers • Pulmonary stretch receptors • Excited by inflation of the lungs • Protect against overinflation; not too important in regular breathing • Chemoreceptors • Located in aortic and carotid bodies, medulla • Sample pO2 and pCO2 in blood

  6. Under anaerobic conditions: • No O2 available as final e- acceptor • Reducing equivalents build up • TCA cycle no longer functional • Can’t use fats or proteins for energy • Can’t transfer reducing equivalents • across mitochondrial membrane • Reduced NADH builds up in cytoplasm • Lack of NAD+ limits glycolysis Need alternative pathway for reconverting NADH to NAD+

  7. Trout - Environmental Hypoxia Aerated Hypoxic PO2 (mm Hg) 155 30 Breathing rate (min-1) 85 120 Ventilation vol. (ml•min-1) 500 3500 • VO2 (ml O2•kg-1•h-1) 100 100 Blood lactate (mg•100ml-1) 12.77 34.86

  8. Lactate Pathway NADH NAD+ pyruvate lactic acid LDH lactate + H+ LDH = lactate dehydrogenase

  9. ½O2 H2O lactic acid pyruvate Additional O2 required after cessation of exercise to “repay the O2 debt”

  10. PEPCK oxa mal H+ fum suc PEPCK = phosphoenolpyruvate carboxykinase Alternative Anaerobic Pathways 1) Succinate/propionate pathway Glucose PK (= pyruvate kinase) PEP pyruvate acetyl-CoA oxa citrate a-KG mal TCA suc-CoA fum suc

  11. CoA 2 ATP 2 ADP 2 SUC-CoA 2 Me-MAL-CoA 2 ADP 2 ATP CO2 2 propionyl-CoA 2 ADP 2 ATP CoA 2 propionate 2 NADH 2 NAD+ PEPCK 2 PEP 2 OXA 2 SUC 2 ADP 2 ATP 2 ADP 2 ATP Advantages: • +4 ATP to SUC • +4 ATP to propionate • useful - fatty acids • less acidic than l.a.

More Related