Oxygen transport ppt

Cards (39)

  • 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