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Carriage of Oxygen

Carriage of Oxygen

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Carriage of Oxygen

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  1. Carriage of Oxygen Aims: To learn the role of haemoglobin in carrying oxygen To learn the significance of the different affinities for oxygen of fetal and adult haemoglobin

  2. Hb has a high affinity for oxygen where oxygen concentration is high.

  3. Oxygen Transport • At low levels of oxygen Hb does not readily take up oxygen, therefore there is a low saturation • When one oxygen molecule binds with Hb it changes the shape of the protein, making it easier for other oxygen to join (steepness of curve) • Once three molecules of oxygen, it is more difficult for the fourth to join (curve levels off)

  4. Fetal haemoglobin • Higher affinity for oxygen than adult Hb at any given partial pressure of oxygen. • Fetal Hb will receive oxygen from maternal Hb at same partial pressure of oxygen. • Curve is then positioned to the left. • Why is this necessary? (4)

  5. Myoglobin. • Fetal Hb is positioned to the left. • Myoglobin is a different pigment which acts an oxygen store. It stays permanently in muscles and does not travel in the blood.

  6. Myoglobin • Pigment found in muscles, takes up oxygen much more readily than Hb.

  7. Comparing pigments. Sketch a graph showing the relative differences between the following: • Myoglobin (Oxygen store) • Human fetal Hb • Llama Hb (High altitude) • Adult Hb • Bird Hb (High Resp Rate)

  8. Low Oxygen partial pressure Q’s The prairie dog spends much of it’s time resting in underground burrows where the oxygen partial pressure is low. Predict whether it’s haemoglobin curve will be positioned to left or to the right, compared to adult Hb? Ans – Positioned to left compared to adult Hb. It will have a higher affinity for oxygen enabling it to obtain enough oxygen even though the partial pressure in the burrow is very low.

  9. Carriage of Carbon dioxide Aims: To describe the role of Hb in carrying carbon dioxide To describe and explain the significance of the Bohr effect

  10. Transport of CO2 • How can CO2 be transported? 5% dissolved in plasma 10% binds to Hb (carbaminohaemoglobin) 85% converted to hydrogencarbonate ions and is transported in plasma.

  11. Carbon dioxide diffuses into blood, some enters RBC & forms carbonic acid • Catalysed by carbonic anhydrase • CO2 + H2O H2CO3 • This dissociates • H2CO3 HCO3- + H+ • HCO3- diffuses into plasma, chloride ions go into RBCto balance charge

  12. The left over H ions could make the RBC very acidic • Therefore the Hb takes up the H ions to make haemoglobinic acid. • What is this called?

  13. The Bohr Effect. • An increase in carbon dioxide concentration will reduce the affinity of Hb for oxygen, moving the oxygen dissociation curve of Hb to the right. This causes the release of more oxygen to the respiring tissues.

  14. Factors affecting curve. • Partial pressure of CO2 • Temp • pH Increasing carbon dioxide makes conditions more acidic (lower pH). So acidity will decrease affinity and move curve to the right.

  15. Oxygen Dissociation curve.

  16. REVISION PRESENTATIONS 1.Double Circulation. 2.Structure of Heart 3.Cardiac Cycle 4.Rate of Heart Beat 5.Heart Excitation 6.ECG 7.Blood Vessels 8.Blood Cells 9.Oxygen Transport in Hb.