Oxygen transport ppt

• Haemoglobin

  Protein with a quaternary structure made up of four polypeptide chains, each with a haem group containing an iron ion. Responsible for oxygen transport in red blood cells of mammals, birds and fish.
• Deoxygenated blood contains haemoglobin
• Oxygenated blood contains haemoglobin
• Haemoglobin


  • Found in red blood cells
  • In the blood of mammals, birds and fish
  • A group of chemically similar molecules
  • Quaternary protein
  • Has 4 polypeptide chains associated together
• Oxygen loading/associating with haemoglobin

  Oxygen loads to/associates with haemoglobin to form oxyhaemoglobin
• Cooperative nature of oxygen binding

  • First O2 molecule binds and causes a change in shape of Hb which makes it easier for the other O2 molecules to bind
  • How readily haemoglobin loads/associates with oxygen is called its affinity for oxygen
  • Haemoglobin's affinity for oxygen changes as the oxygen's concentration varies through the body
• Affinity for oxygen


  How readily haemoglobin loads/associates with oxygen
• At the gas exchange surface

  Partial pressure of O2 (ppO2) is high, so Hb has a high affinity for oxygen and loads readily
• At the tissues


  Partial pressure of O2 (ppO2) is lower, so Hb has a lower affinity for oxygen and unloads readily
• Haemoglobin changes its affinity for oxygen under different conditions
• Affinity


  Ability to load/bind with oxygen
• High affinity for oxygen

  Oxygen loads to Hb
• Low affinity for oxygen

  Oxygen unloads from Hb
• Oxygen dissociation curve


  • At the gas exchange surface, high ppO2 means Hb has high affinity so loads readily, resulting in high % saturation
  • At the tissues, lower ppO2 means Hb has lower affinity so unloads readily, resulting in lower % saturation
• Increase in ppCO2


  Causes the oxygen dissociation curve to shift right (Bohr shift), reducing Hb's affinity for oxygen
• Higher ppCO2


  At the same ppO2, the % saturation of Hb is lower, so more O2 is unloaded to cells
• Different haemoglobins


  • Have different affinities for oxygen
  • High affinity haemoglobins load oxygen readily
  • Low affinity haemoglobins unload oxygen readily
• Low oxygen environments

  Hb has a higher affinity for O2, so loads more readily at the lower ppO2 available
• Hb with high affinity for oxygen


  • Oxygen dissociation curve lies to the left
  • Fully loads at lower ppO2
  • Steeper curve ensures only small drop in ppO2 gives large drop in % saturation to dissociate oxygen to respiring cells
• Hb with low affinity for oxygen


  • Oxygen dissociation curve lies to the right
  • Necessary for organisms with high oxygen demand and high rate of respiration
• Curve to the left

  Loads oxygen readily
• Curve to the right


  Releases (unloads) oxygen readily
• The animal's haemoglobin has the affinity for oxygen, not the animal itself
• Haemoglobin

  • Has 4 haem groups, each one has an iron ion in the centre
  • One oxygen molecule can bind to one haem group so a total of 4 oxygen molecules can be carried by one Hb
  • When oxygen is bound to Hb it is called oxyhaemoglobin
• Describe how oxygen loads

  • At the GE surface the partial pressure of oxygen is high
  • oxygen diffuses down a conc. gradient from alveoli into the red blood cells
  • Haemoglobin has a high affinity for oxygen due to a high partial pressure of oxygen
  • Therefore it loads/associates with oxygen readily (cooperative nature etc)
  • Red blood cells travel in the blood-mass transport-to tissues
• Describe how oxygen is unloaded

  • At the tissues the partial pressure of oxygen is lower (as the O2 is used in respiration)
  • Haemoglobin has a lower affinity for oxygen due to lower partial pressure of oxygen
  • Therefore it unloads/disassociates oxygen
  • Oxygen diffuses down a conc. gradient from the red blood cells to the tissues
• Haemoglobins affinity for O2 changes under different conditions

  • Lungs- (ppO2)=high THEREFORE Hb's affinity for O2= high Result=O2 loads to haemoglobin
  • Respiring tissues-(ppO2)=low THEREFORE Hb's affinity for O2 is low Results= O2 unloads from the haemoglobin
• What is the affinity?

  The ability to load/bind with oxygen
• The change in Hb’s affinity for oxygen at different partial pressures of oxygen

  
• Change in Hb’s affinity for oxygen at different partial pressures of oxygen

  
• Influence of CO2 (ppCO2) on the dissociated of O2 from Hb

  
• How ppCO2 influences oxygen dissociation from Hb

  
• For the influence on oxygen dissociation from Hb what would happen if the pCO2 was high? How much saturation? Load or unload? and what would happen if pCO2 was low?

  • High pCO2=lower % saturation of haemoglobin so unloads more readily
  • Low pCO2=higher % saturation of haemoglobin so loads readily
• Haemoglobins have different affinities for oxygen

  • High affinity= Loads/associates with oxygen readily
  • Low affinity= Unloads/dissociates from oxygen readily
• In low oxygen environments

  • Hb has a high affinity for O2
  • So, loads more readily at the lower ppO2 available So what would the graph look like?
  • Needs Hb with a higher affinity for O2 so will load more readily at the lower ppO2 available
  • O2 dissociation curve lies to the left
• Low oxygen environments need Hb with a higher affinity for oxygen so will load more readily at the lower ppO2 available

  
• Why do some animals require a high rate of respiration?

  • Large SA:V
  • They are active (more energy required for movement etc)
• Large S:A or very active animals have a high rate of aerobic respiration so, need Hb with a lower affinity for oxygen so it will unload more readily

  
• Organisms that need haemoglobin with a low affinity for oxygen

  • ACTIVE ANIMALS
  • high rate of respiration=high demand for O2 release= O2 unloads readily from Hb
  • LARGE SA:V
  • loses more heat so higher rate of respiration to maintain body temp, so higher demand for O2 release=unloads CO2 readily