Transport of Oxygen and CO2

• What is the primary function of animal transport in relation to gases?

  Carriage of O₂ and CO₂
• How is oxygen transported in the blood?

  Oxygen is transported in erythrocytes by haemoglobin
• What happens to oxygen when it binds with haemoglobin?

  Oxygen combines with haemoglobin to form oxyhaemoglobin
• Where is oxygen taken up and released in the body?

  Oxygen is taken up in the lungs and released in body tissues
• What is the structure of haemoglobin?

  Haemoglobin is a complex protein with 4 subunits
• What does each subunit of haemoglobin contain?

  Each subunit has a polypeptide chain and a haem group
• What ion is found in the haem group of haemoglobin?

  The haem group contains an Fe²⁺ ion
• What is the affinity of the haem group for oxygen?

  The haem group has an affinity for oxygen
• How many oxygen molecules can one haemoglobin molecule hold?

  One haemoglobin molecule can hold four oxygen molecules
• What factors affect the ability of haemoglobin to take up oxygen?

  The ability of haemoglobin to take up oxygen depends on oxygen levels in surrounding tissues
• How is the amount of oxygen measured?

  The amount of oxygen is measured by partial pressure (pO₂)
• What does partial pressure represent?

  Partial pressure represents the relative pressure that O₂ contributes in the mix of gases
• In what units is partial pressure measured?

  Partial pressure is measured in kPa
• How does haemoglobin's affinity for oxygen change with partial pressure?

  At high partial pressures of oxygen, haemoglobin has a high affinity for oxygen
• What occurs at low partial pressures of oxygen?

  At low partial pressures of oxygen, haemoglobin has a low affinity for oxygen
• What is the oxygen partial pressure in the lungs?

  The oxygen partial pressure in the lungs is high enough to produce almost 100% saturation
• What is the oxygen partial pressure in body tissues?

  The oxygen partial pressure in body tissues is low enough to cause dissociation
• What is the oxyhaemoglobin dissociation curve?

  • Graph showing the relationship between pO₂ and haemoglobin saturation
  • At high pO₂, haemoglobin saturation is high
  • Conformational change occurs after first binding, increasing uptake
  • At low pO₂, oxygen is not readily taken up
• What happens to haemoglobin at 100% saturation?

  At 100% saturation, 4 molecules of oxygen are bound to each haemoglobin
• How does pO₂ affect haemoglobin's affinity for oxygen?

  At high pO₂, haemoglobin has a high affinity for O₂
• What is the role of foetal haemoglobin compared to adult haemoglobin?

  Foetal haemoglobin has a higher affinity for oxygen than adult haemoglobin
• Where does oxygen exchange occur for foetal haemoglobin?

  Oxygen exchange occurs in the placenta
• How does CO₂ affect the affinity of haemoglobin for oxygen?

  CO₂ reduces the affinity of haemoglobin for oxygen
• What is the Bohr effect?

  The Bohr effect is the shift of the oxygen dissociation curve to the right due to CO₂
• How does CO₂ assist in unloading oxygen to tissues?

  CO₂ assists in unloading oxygen by reducing the affinity of haemoglobin for oxygen
• How do oxygen dissociation curves compare among different organisms?

  • Curves further to the left indicate higher affinity for oxygen
  • Organisms in low O₂ environments have left-shifted curves
  • Active organisms with high metabolic rates have right-shifted curves
• How is CO₂ transported from tissues to lungs?

  CO₂ is transported in three ways: dissolved in plasma, as carbaminohaemoglobin, and as hydrogencarbonate ions
• What percentage of CO₂ is transported as hydrogencarbonate ions?

  85% of CO₂ is transported as hydrogencarbonate ions
• What happens to CO₂ when it diffuses into the blood?

  CO₂ combines with water to form carbonic acid in the presence of carbonic anhydrase
• What is the reaction for the formation of hydrogencarbonate ions?

  CO₂ + H₂O ⇌ H₂CO₃ ⇌ HCO₃^- + H⁺
• What maintains the electrochemical charge of red blood cells?

  The electrochemical charge of red blood cells is maintained by the movement of chloride ions (Cl^-) from plasma to erythrocytes
• What is the chloride shift?

  The chloride shift is the movement of chloride ions into erythrocytes
• How does haemoglobin act as a buffer in the blood?

  Haemoglobin binds with H⁺ ions to produce haemoglobinic acid
• What happens to oxyhaemoglobin during the release of oxygen?

  Oxyhaemoglobin dissociates, freeing O₂ to be released into the plasma
• How is CO₂ carried in the blood?

  • 5% dissolved in plasma
  • 10% as carbaminohaemoglobin
  • 85% as hydrogencarbonate ions
• What is the role of carbonic anhydrase in CO₂ transport?

  Carbonic anhydrase catalyzes the formation of carbonic acid from CO₂ and water
• What is facilitated diffusion in the context of CO₂ transport?

  Facilitated diffusion refers to the movement of CO₂ across membranes with the help of transport proteins
• What is co-transport in the context of CO₂ transport?

  Co-transport involves the simultaneous transport of CO₂ and chloride ions
• How does CO₂ diffuse in the blood?

  CO₂ diffuses from tissues into the plasma and erythrocytes
• What is the significance of the chloride shift in CO₂ transport?

  The chloride shift helps maintain the electrochemical balance in red blood cells