Haemoglobin

Is a protein consisting of:

• 4 Polypeptide chains
• These are coiled into a helix
• Which is folded into a specific shape
  
• These are linked to form a spherical molecule.
  

Each polypeptide is associated with a haem group, containing and Fe2+ ion.

Ferrous (Fe2+)attaches to the middle of the heam group.

Hb+ 4O2 = HbO8
or
Haemoglobin + Oxygen = Oxyhaemoglobin

Has to associate/load with oxygen in the lungs. High affinity. Disociates at the tissues that require it.

Carbon Dioxide makes a weak acid when in water (solution), this changes the pH, and therefore, the shape of the protein, (temporarily.)

Why can haemoglobin unload? :

• Low partial pressure of O2 means the oxygen is used in aerobic respiration, which means there is a higher CO2 concentration.
  
• This reduces the pH (as CO2 is acidic in solution)
  
• Haemoglobin changes it's shape in high CO2 concentrations.
  
• This means it binds to the oxygen more loosely.
  
• And can, therefore, unload where needed.
  

Erythrocytes- Red Blood Cells
Leucocytes- White Blood Cells.

Plasma % in blood is important, makes it fluid, and flows easier.

Adaptations of a red blood cell:

• Small size (7 micrometres.)
  
• Flattened biconcave disc shape.
• Thin central section
• Absence of organelles.
  
• Filled with haemoglobin

Oxygen dissasociation curve: Shows how much oxygen is combined with Hb at different concentrations of oxygen.

Haemoglobin is never 100% saturated.

Pp of oxygen is lower in lungs due to presence of CO2 and water vapour so it would be less.

Thoughts?
-Nin.