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8.5 Blood - Coggle Diagram

- - - - When a haem group gains an oxygen, a conformational shape change occurs and the whole haemoglobin molecule distorts
      - In a dissociation curve, the gradient is not steep at first because it is harder to add the first oxygen molecule to the first haem group
      - Then the gradient quickly becomes steep, as after the first oxygen molecule is added to the first haem group, the conformational shape change means other oxygen molecules can now bind more easily to the remaining haem groups
      - This is why a dissociation curve is S-shaped
    - - Haemoglobin is also affected by partial pressure of carbon dioxide
        
        Higher partial pressure = lower oxygen saturation of haemoglobin
        
        Oxygen is more easily released when haemoglobin is in environment of high carbon dioxide concentration
        
        This is useful because high carbon dioxide concentrations are found in respiring muscles which need lots of oxygen deposited for further respiration
        
        The dissociation curve shifts to the right
      - Carbon dioxide is produced by respiring cells, which then diffuses into blood plasma
        
        RBC cytoplasm contains carbonic anhydrase
        
        Carbon dioxide is converted to carbonic acid
        
        Carbonic acid dissociates to form H+, making the blood more acidic
        
        Haemoglobin combines with H+ to form haemoglobinic acid
        
        Haemoglobin acts as a buffer for blood pH
        
        When this occurs, haemoglobin releases its oxygen molecules
        
        When lots of the H+ is removed and HCO3- is left behind in the blood plasma, a negative charge is formed
        
        Chloride ions move from blood plasma into RBCs to balance charge (chloride shift)
        
        HCO3- is pumped out of RBCs via transport proteins
  - - - Increases surface area:volume ratio, so increases rate of oxygen diffusion
    - - Haemoglobin never far from cell surface membrane
      - Allows capillaries to be very small, meaning more vessels can be present so more cells are close to oxygen supply
    - - Cells can be compacted to fit more into tighter spaces
      - They have a specialised cytoskeleton which allows them to be compressed and then spring back to original form
    - - More room for haemoglobin, so more oxygen stored