Oxygen Dissociation Curve.pptx a breif description

Oxygen dissociation curve

1. Oxygen Dissociation Curve Dr. Riya Sahebrao Divekar

2. Introduction OXYGEN TRANSPORT: Oxygen diffuses into the plasma of the Pulmonary capillary blood driven by its concentration gradient from the alveolus Major form for transport of O2 is by combining with Haemoglobin The relationship between these two can be studied with the help of Oxygen Dissociation curve It is an important tool for understanding how Blood carries and releases oxygen

3. Major form(97%)- Oxygen combined with Hb –O2 transport Minor form (3%) - Dissolved form- The quantity of O2 dissolved in plasma is directly proportional to its partial pressure (Henrys Law) PO2 Gas conc= Solubility coefficient X Partial Pressure 0.003ml/mmHg/100 ml blood (solubility coefficient) For PO2 of 100 mm Hg- 0.3 mL of dissolved O2 in 100 ml of blood -Dissolved form – 0.3ml/100ml of blood 1gm Hb- 1.34ml of O2 Hb Increases transport of O2 by 70 times

4. Hemoglobin Heme + Globin: Quaternary Heme- Present as 4 subunits connected by polypeptide globin chains as 2 Alpha and 2 Beta subunits(Adult) Each Heme contains one atom of Ferrous +2 ion Each Ferrous ion has the ability to bind to one Oxygen molecule reversibly

5. Oxygen Cascade- The process of declining oxygen tension from atmosphere to mitochondria (Humidification) O2 Uptake+ Co2 addition + alveolar ventilation) Venous Admixture Tissue extraction

6. Normal Curve Sigmoid shaped curve- co-operative binding kinetics X axis- Partial pressure of oxygen in mmHg Y axis- Hemoglobin Oxygen Saturation At PO2 of 100mm of Hg, the curve reaches a Plateau Phase where no more Hb is available to combine with oxygen P50 Value- It is the partial pressure of oxygen at which Oxygen and Hb are 50 % saturated 50% O2-Hb saturation happens at a PO2 level of- 26.6mm of Hg (3.4 kPa)

7. A rightward shift in the curve lowers O2 affinity, displaces O2 from Hemoglobin, and makes more O2 available to tissues A leftward shift increases hemoglobin’s affinity for O2, reducing its availability to tissues

8. LEFT SHIFT RIGHT SHIFT -P50 decreases Hypocarbia Alkalosis Fetal Haemoglobin ( HbF )- very high affinity to O2, less affinity to 2, 3 BPG Carbon Monoxide Stored Blood – Inhibition of glycolysis- fall in 2,3 BPG. Blood stored in CPDA Citrate Phosphate dextrose Adenine P50 increases Hypoxia Hypercarbia Decreased Ph Acidity Anaerobic Glycolysis-> 2,3 Bi Phospho Glycerate. ( 2,3 BPG) Prolonged Hypoxia at High Altitude Exercise Chronic Acidosis- inhibition of glycolytic enzymes- decreased 2,3 BPG

9. Haldane effect- Loading of O2 by Hb and release of CO2- Lungs-Left shift Bohr’s effect- An increase in Blood Hydrogen ion concentration reduces O2 binding to Hemoglobin i.e. Unloading of O2- Right Shift- Release of O2 at tissue level

10. Thank You