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19 Cards in this Set
- Front
- Back
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What is haemoglobin? |
- protein with quarternary structure - 4 polypeptide chains each attached to haem group (Fe2+) |
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What is the capacity of haemoglobin? Give the reason. |
- Haemoglobin = 4 oxygen molecules - each haem group can bind to one oxygen molecule |
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What is loading/associating? |
- The process where haemoglobin binds with oxygen - in humans = occurs in the lungs |
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What is unloading/dissociating? |
- The process where haemoglobin releases oxygen - in humans = occurs near tissues |
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What does it mean when Hb has a high affinity? |
- Hb will take up oxygen easily - release oxygen less easily |
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What does it mean when Hb has a low affinity? |
- Hb will take up oxygen less easily - release oxygen easily |
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What must Hb do to transport oxygen efficiently? How does it do this? |
- Must easily associate with oxygen at lungs - Readily dissociate from oxygen at tissues - achieved by Hb changing affinity in different conditions |
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Why are there different types of haemoglobins in different organisms? |
- different properties to how they take up/release oxygen - each species=slightly different amino acid sequence for Hb=different oxygen binding properties (high/low affinity) |
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What does an oxygen dissociation curve show? |
- the relationship between Hb saturation and oxygen partial pressure |
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What is the explanation for the shape of the oxygen dissociation curve? |
- shape of Hb molecule=hard for 1st oxygen to bind to one haem=closely united;low partial pressure=little oxygen binds to Hb (shallow) - 1st binding makes Hb shape change=easier for oxygen to bind;smaller partial pressure increase to bind second oxygen (positive cooperativity) - after 3rd oxygen binds, 4th oxygen harder to bind (probability)=curve flattens |
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What are the two facts about oxygen dissociation curves? |
- Further left=higher affinity - Further right=lower affinity |
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What adaptations do erythrocytes have which aids their function? |
- Biconcave shape maximises SA=gas exchange - small/flexible to pass through narrow capillaries - no nucleus=more room to carry respiratory gases - Packed with haemoglobin |
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What is the Bohr Effect? |
- Greater carbon dioxide concentration = Hb more readily releases oxygen |
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How does the Bohr effect explain why Hb behaviour changes in different regions of the body? |
- At lungs: conc. of CO2 low=high affinity+high O2 conc.=O2 binds readily - Respiring cells: CO2 conc. high=low affinity+low O2 conc.=O2 unloads readily |
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Why does carbon dioxide change the affinity of Hb? |
- Dissolved CO2=acidic=low pH=Hb changes shape |
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What are the properties of foetal haemoglobin? |
- RBC in foetal bloodstream contain special form of Hb - higher affinity for O2 than adult Hb - Maximise O2 uptake from mother's bloodstream |
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What is myloglobin? |
- molecule with similar structure to Hb, but only one haem group - high affinity for O2, even at low partial pressure - oxymyloglobin dissociates when O2 levels low - found in muscle cells=acts as O2 reserve |
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How does the body acclimate to higher altitudes? |
- increased heart rate/breathing/conc. of blood/RBC production - Hb picks up and offloads O2 more efficiently |
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What are the different ways in which CO2 is transported to the lungs? |
~5%:dissolved as CO2 in blood plasma ~10%: diffuses into RBCs/combines with Hb=carbaminohaemoglobin ~85%: in solution in the plasma as hydrogen carbonate |
