Haemoglobin

• How is tissue fluid formed at the arteriole end?

  Hydrostatic pressure forces fluid out of capillaries
• How is tissue fluid returned to the blood at the venule end?

  Osmotic pressure draws fluid back into blood
• What is the role of lymph vessels in tissue fluid?

  They drain excess fluid back to blood
• Describe the structure of a protein.

  • Primary: sequence of amino acids
  • Secondary: hydrogen bonds form alpha helix and beta sheets
  • Tertiary: 3D shape from folding polypeptide chains
  • Quaternary: multiple polypeptide chains linked together
• What is Littorina littorea?

  A species of snail found on rocky shores
• How can a student ensure reliable samples of snails?

  Select samples at random and use large numbers
• What is the partial pressure of oxygen (pO2)?

  A measure of oxygen concentration
• Where is pO2 high and low in the body?

  High in lungs, low in muscle tissues
• What happens to oxygen at high pO2?

  Oxygen associates with haemoglobin to form oxyhaemoglobin
• What happens to oxygen at low pO2?

  Oxygen dissociates from haemoglobin
• What inorganic ion makes up the haem group?

  Fe2+
• How many haem groups does a haemoglobin have?

  Four haem groups
• What is the shape of a red blood cell?

  Biconcave disc
• What term describes the oxygen concentration in the body?

  Partial pressure (pO2)
• Where in the body would you find a low pO2?

  In respiring tissues
• What term describes oxygen binding with haemoglobin?

  Associating (or loading)
• What term describes haemoglobin releasing oxygen?

  Dissociating (or unloading)
• In which part of the body does oxygen associate with haemoglobin?

  In the lungs
• Why is the oxygen dissociation curve S-shaped?

  It shows non-linear binding of oxygen
• What happens at higher partial pressures of oxygen?

  Little change in haemoglobin saturation
• What happens at lower partial pressures of oxygen?

  Small changes can lead to large saturation changes
• Why does the curve flatten at the top?

  Joining the fourth O2 is more difficult
• What is positive cooperativity in haemoglobin?

  Binding of one O2 makes it easier for others
• How does oxygen binding affect haemoglobin's shape?

  It causes a slight shape change in haemoglobin
• Why does the fourth oxygen struggle to bind?

  Most binding sites are already occupied
• What are the key ideas about oxygen affinity in haemoglobin?

  • Loading: haemoglobin binds with oxygen in lungs
  • Unloading: haemoglobin releases oxygen in tissues
  • High affinity: takes up oxygen easily, releases less
  • Low affinity: takes up oxygen less easily, releases more
• What are the structural features of red blood cells?

  • Biconcave shape for gas exchange
  • Lack of nucleus for more haemoglobin
  • Flexible membrane for passing through capillaries
  • No organelles to maximize space for haemoglobin
• What is the importance of understanding haemoglobin structure?

  • Essential for oxygen transport
  • Related to respiration processes
  • Links to future biological topics
• What is the process of oxygen loading in the blood?

  Oxygen loading occurs in the lungs.
• Why does haemoglobin lose oxygen more readily during exercise?

  Cells respire faster and need more oxygen.
• What is the Bohr effect in relation to oxygen dissociation?

  It shifts the dissociation curve to the right.
• What happens to the saturation of haemoglobin with O2 at a given pO2 during exercise?

  It becomes lower due to more oxygen release.
• How do H+ ions affect oxygen release from haemoglobin?

  They cause the release of oxygen from haemoglobin.
• What role does carbonic anhydrase play in oxygen transport?

  It catalyses the reaction between CO₂ and water.
• What ions diffuse into the plasma during the chloride shift?

  HCO3- ions diffuse into the plasma.
• What is the effect of increased blood temperature during exercise on haemoglobin?

  It reduces haemoglobin's affinity for O₂.
• How does a decrease in blood pH affect oxygen delivery during exercise?

  It reduces haemoglobin's affinity for O₂.
• What are the three types of haemoglobin found in humans?

  Adult haemoglobin, foetal haemoglobin, myoglobin.
• Why does foetal haemoglobin have a higher affinity for oxygen than adult haemoglobin?

  It allows efficient oxygen extraction from maternal blood.
• What happens to foetal haemoglobin after birth?

  It is gradually replaced by adult haemoglobin.