Transport of oxygen and carbon dioxide

Summary

The transport of oxygen and carbon dioxide in mammals involves red blood cells, plasma, and various physiological processes to ensure efficient gas exchange. The oxygen dissociation curve and the Bohr shift are key concepts in understanding how oxygen is released in tissues and how carbon dioxide is transported.

• Red Blood Cells — cells that contain hemoglobin for carrying oxygen. Example: Oxyhaemoglobin is formed when oxygen binds to hemoglobin.
• The Chloride Shift — the movement of chloride ions into red blood cells as hydrogen carbonate ions are formed. Example: This shift helps maintain electrical neutrality in red blood cells.
• Plasma & Carbon Dioxide — plasma carries carbon dioxide in various forms, including hydrogen carbonate ions. Example: About 70% of carbon dioxide is transported as hydrogen carbonate ions.
• The Oxygen Dissociation Curve — a graph showing hemoglobin's oxygen binding at different partial pressures. Example: Hemoglobin has a lower affinity for oxygen at low partial pressures.
• The Bohr Shift — a shift in the oxygen dissociation curve due to increased carbon dioxide levels. Example: This shift facilitates oxygen release in respiring tissues.

Exam Tips

Key Definitions to Remember

• Red Blood Cells: Cells that carry oxygen using hemoglobin.
• The Chloride Shift: Movement of chloride ions into red blood cells to balance charge.
• The Oxygen Dissociation Curve: Graph showing hemoglobin's oxygen binding at different pressures.
• The Bohr Shift: Change in the dissociation curve due to CO2 levels affecting oxygen release.

Common Confusions

• Confusing the role of hemoglobin with that of plasma in oxygen transport.
• Misunderstanding the significance of the Bohr shift in oxygen delivery.

Typical Exam Questions

• How does oxyhaemoglobin formation increase oxygen transport capacity? Oxyhaemoglobin formation allows red blood cells to carry more oxygen.
• What effect does increasing CO2 concentration have on oxygen dissociation? It increases oxygen dissociation from hemoglobin in tissues.
• Which curve shows the lowest pH and where might this data be collected? The curve with the lowest pH is typically found in respiring tissues.

What Examiners Usually Test

• Understanding of how oxygen and carbon dioxide are transported in the blood.
• The significance of the oxygen dissociation curve and the Bohr shift.