Gas Exchange

• The Bohr effect states that increased concentration of CO2 and protons reduce affinity of haemoglobin to oxygen
• Higher pCO2 increases the amount of H+ produced, which reduces the binding of O2 by Haemoglobin
• Factors that reduce affinity are:

  • Low pH (increase H+)
  • Increase in CO2
  • Elevated temperature
  • Organic compounds
• What is Bohr effect?

  Changes of conformation molecules and binding site for O2 due to CO2 and H+ binding to haemoglobin (allosteric site)
• Allosteric site binds with CO2 and H+
• Increase in temperature, decreases O2 affinity (shifts to the right)
• At low P02, there is little oxygen available so it has high affinity for haemoglobin
• As P02 increases, more oxygen is available so less is bound to haemoglobin
• Oxygen saturation curve shows how much oxygen can be carried at different partial pressures.
• Oxygen dissociation curve shows how much oxygen will be bound at different partial pressures.
• As PO2 increase, more oxygen dissociates from haemoglobin
• The shape of an oxyhaemoglobin dissociation curve depends on factors such as pH, temperature, and concentration of carbon dioxide.
• CO2 dissociation curve is called Haldane effects
• Bohr effect - the affinity of haemoglobin for O2 decreases as the amount of CO2 increases
• Higher levels of CO2 cause greater release of O2 by haemoglobin
• Bohr effect and Haldane effects - increasing CO2, decreasing affinity of haemoglobin for O2 hence CO2 bind more easily
• Factors that affects rate of gas transfer

  • partial pressure gradient
  • SA of respiratory organ
  • Thickness of membrane
• Explain the process of CO2 transfer in tissues

  CO2 enters RBC from tissues and reacts with water forming HCO3 with the help of enzyme carbonic anhydrase, and transported out of RBC (chloride shift)
• Bird need unidirectional, high rates of ventilation because high O2 consumption and high metabolic rates
• Four factors that increase O2 transfer in the chicken egg

  • O2 affinity of Hb
  • gradient of O2 pressure
  • Blood flows and volume
• When a beetle dives in water with an air bubble, the life of bubble depends on hydodrastic pressure and metabolic rate