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| Question | Answer |
| Describe the structure of haemoglobin | Haemoglobin is made up of 4 polypeptide chains, each with a haem group which contains iron |
| How many oxygen molecules can each haemoglobin carry? | Each haemoglobin can carry 4 oxygen molecules Association Hb + 4O₂ ⇌ HbO₈ Dissociation |
| What is oxygen affinity? | The tendency a molecule has to bind with O₂ |
| What affects oxygen affinity? | Partial pressure of oxygen (pO₂) The greater the concentration of dissolved O₂ in cells, the higher the pO₂. As pO₂ increases, affinity increases. |
| TRUE OR FALSE: Alveoli have a high pO₂ | TRUE Alveoli have a high pO₂ so O₂ associates with haemoglobin |
| TRUE OR FALSE: Cells that respire have a high pO₂ | FALSE Cells that respire have a LOW pO₂ |
| What is the oxyhaemoglobin dissociation curve? | The oxyhaemoglobin dissociation curve is a curve that plots the proportion of haemoglobin in its saturated form on the vertical axis against the partial pressure of oxygen on the horizontal axis |
| Complete the sentences: When haemoglobin combines with the first O₂, the shape alters, making it _________ for other O₂ to join too. HOWEVER! As haemoglobin starts to become saturated, it gets ____________ for O₂ to join. | When haemoglobin combines with the first O₂, the shape alters, making it EASIER for other O₂ to join too. HOWEVER! As haemoglobin starts to become saturated, it gets HARDER for O₂ to join. |
| How does the dissociation curve of foetal haemoglobin compare to that of adult haemoglobin? | By the time the mother's blood reaches the placenta, its oxygen saturation has decreased as some have been used up by the mother's body. The placenta has a low pO₂ so adult haemoglobin will dissociate. For the foetus to get enough oxygen, it must have a higher affinity, so that it can take up O₂ in lower pO₂ than adult haemoglobin. |
| What does the oxyhaemoglobin dissociation curve look like for foetal haemoglobin and adult haemoglobin? |
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| How does carbon dioxide affect dissociation? | Haemoglobin gives O₂ more readily at a higher pCO₂. When cells respire, they raise O₂, increasing the rate of dissociation. More O₂ is being released |
| What is the Bohr effect? | A physiological phenomenon stating that haemoglobin's oxygen binding affinity is inversely related both to acidity and to the concentration of carbon dioxide |
| Outline the process in which CO₂ binds to a red blood cell |
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| What happens when the blood reaches the lungs? | When the blood reaches the lungs, the low pCO₂ causes some of the HCO₃⁻ ions and H⁺ ions to recombine into CO₂ and H₂O. The CO₂ is then diffused into the alveoli and breathed out |
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