Dissociation curves of oxyhaemoglobin

• Define partial pressure.

  The pressure exerted by a gas in a mixture measured usually in kPa

  Often used to represent the concentration of a gas
• What shape is the dissociation curve of oxyhaemoglobin?

  S-shaped
• What does the gradient represent in the dissociation curve of oxyhaemoglobin?

  How easily Hb loads oxygen at a given point
• Describe the oxyhaemoglobin dissociation curve.

  • oxygen is loaded in regions with high partial pressures (alveoli)
  • unloaded in regions of low partial pressure (respiring tissue)

  A) respiring tissues

  B) alveoli

  
• Complete the following about when the oxyhaemoglobin curve shifts left.

  • Hb would have a higher affinity for oxygen
  • load more at the same partial pressure
  • becomes more saturated
  • adaptation in low-oxygen environments
  • e.g. llamas/ in foetuses
• What is cooperative binding?

  • Hb's affinity for oxygen increases as more oxygen molecules are associated with it
  • when one binds, Hb changes shape meaning others bind more easily
  • explaining S shape of curve
• How does carbon dioxide affect haemoglobin?

  • When carbon dioxide dissolves in liquid, carbonic acid forms
  • decreases pH causing Hb to change shape
  • affinity decreases at respiring tissues
  • more oxygen is unloaded
• What is the Bohr effect and what does it do to haemoglobin?

  • High carbon dioxide partial pressure
  • causes oxyhaemoglobin curve to shift to the right
• Complete the following about the oxyhaemoglobin curve shifting right.

  • Hb has lower affinity for oxygen
  • unloads more at the same partial pressures
  • less saturated
  • present in animals with faster metabolisms that need more oxygen for respiration
  • e.g. birds/rodents