Oxygen and carbon dioxide

• How is oxygen carried in the blood?

  By haemoglobin forming oxyhaemoglobin
• What is the role of the Fe²⁺ ion in haemoglobin?

  It allows haemoglobin to carry four oxygen molecules
• How does haemoglobin maintain a steep oxygen concentration gradient?

  By taking up oxygen as it diffuses into blood
• What is meant by the dissociation of oxyhaemoglobin?

  Release of oxygen from haemoglobin in tissues
• What two properties must haemoglobin have to be effective?

  • Readily associate with oxygen at gas exchange
  • Readily dissociate from oxygen at respiring tissues
• How does haemoglobin change its affinity for oxygen?

  By undergoing conformational changes based on gas levels
• How does oxygen tension affect haemoglobin’s affinity for oxygen at a gas exchange surface?

  High oxygen tension increases haemoglobin's affinity
• How does oxygen tension affect haemoglobin’s affinity for oxygen at respiring tissues?

  Low oxygen tension decreases haemoglobin's affinity
• What does an oxyhaemoglobin dissociation curve show?

  Haemoglobin saturation at different oxygen concentrations
• What is partial pressure (pO₂)?

  Concentration of dissolved oxygen in an environment
• Why is haemoglobin’s saturation low at low oxygen tension?

  Haem groups are difficult to bind at low tension
• Why does haemoglobin bind oxygen more easily as oxygen tension increases?

  Conformational change occurs after first oxygen binds
• Why does the dissociation curve level off at very high oxygen tension?

  It becomes difficult for the fourth oxygen to bind
• Why must a foetus be able to load oxygen from its mother’s blood?

  Foetus has lower partial pressure of oxygen
• How does foetal haemoglobin help the foetus obtain oxygen?

  It has a higher affinity for oxygen than adult haemoglobin
• How does the dissociation curve of foetal haemoglobin compare to adult haemoglobin?

  It is shifted to the left, indicating higher affinity
• What does it mean when a dissociation curve is shifted to the right?

  Respiratory pigment gives up oxygen more readily
• What is myoglobin and what is its function?

  Myoglobin stores oxygen in muscles for respiration
• How does myoglobin’s affinity for oxygen compare to haemoglobin?

  Myoglobin has a much higher affinity for oxygen
• Why is oxygen concentration lower at high altitudes?

  Decreased air pressure makes oxygen harder to obtain
• What are the effects of high-altitude training?

  1. Water is absorbed from circulation, concentrating RBCs
  2. Kidneys produce more EPO, stimulating RBC production
  3. RBC percentage increases from 45% to 60% after 2-3 weeks
• Why does training at high altitudes improve athletic performance?

  Increased RBC production enhances oxygen-carrying capacity
• How does carbon monoxide affect haemoglobin?

  It binds irreversibly, preventing oxygen transport
• Why is carbon monoxide such an effective poison?

  It has a stronger affinity for haemoglobin than oxygen