BLOOD GASES Flashcards
What is a conjugated protein? (1)
a protein that contains non-polypeptide chemical groups in its structure.
what are erythrocytes? (1)
mammalian red blood cells.
what is a example of a conjugated protein? (1)
haemoglobin is a conjugated protein.
How is oxygen carried by haemoglobin? (2)
oxygen molecules are carried by haemoglobin attached to the haem groups, therefore one haemoglobin molecule can carry for oxygen molecules to form oxyhaemoglobin.
what is meant by partial pressure? (1)
the pressure due to one gas in a mixture of gases. the total pressure of a mixture of gases is made of the sum of partial pressures due to each gas.
what is the law of partial pressures? (2)
the law of partial pressures states that in a mixture of ideal gases, each gas has a partial pressure that is the pressure that the gas would have it it alone occupied the volume. the total pressure of a gas mixture is the sum of the partial pressures of the individual gases in the mixture.
what is the oxygen dissociation curve? (1)
a graph showing the percentage saturation of haemoglobin at different external concentrations of oxygen.
what is the bohr effect? (1)
the reduction of the oxygen-carrying capacity of haemoglobin caused by increasing concentrations of carbon dioxide.
why would we expect it to be a straight line? (2)
because as oxygen molecules combine with haemoglobin they become attached one by one to the four haem groups, the more oxygen that is available, the more haem groups filled.
why is it not a straight line? (2)
because as an oxygen molecule becomes attached it makes it easier for the next two to be taken in, but the final oxygen is more difficult to add, so the graph shows a distinctive s-shape.
what is the effect of the bohr effect on the oxygen dissociation curve?
the oxygen dissociation curve is shifted to the left which gives a boost to the oxygen available at just the point where it is needed most.
why is it important to have haemoglobin in the blood? (1)
because they have a strong affinity for oxygen
what is myoglobin? (1)
a pigment in which muscles contain because of their high oxygen demand.
what does the oxygen dissociation curve look like for myoglobin? (1)
the higher affinity for oxygen will be shown by a oxygen dissociation curve for myoglobin being further to the left than that of haemoglobin.
how does myoglobin achieve a higher affinity? (3)
myoglobin molecules have a modified structure, it is a conjugated protein and carries oxygen attached to a haem group. unlike haemoglobin it only has one haem group attached to a complex globular protein. as a result myoglobin becomes fully saturated at 40kPa which is lower than haemoglobin.
what are the roles of myoglobin? (2)
-assists in the transfer of oxygen from haemoglobin to muscles.
-its strong affinity allows it to form a useful reservoir of oxygen within muscles
why can myoglobin not be used in foetal oxygen exchange? (1)
myoglobin would be unsuitable as their very strong affinity for oxygen would not allow sufficient exchange between foetal blood and the growing tissues.
why is foetal haemoglobin specific in early development? (3)
during the development of the embryo the genes coding for haemoglobin are expressed in varying ways, the result is that haemoglobin proteins undergo subtle changes during development, it has a slightly higher affinity for oxygen than adult haemoglobin but change is enough to transfer oxygen from maternal haemoglobin
what effect does foetal haemoglobin have on the oxygen dissociation curve? (1)
the oxygen dissociation curve shifts to the left.
how is carbon dioxide usually transported? (1)
through the plasma and red blood cells as hydrogen carbonate ions.
what enzyme allows greater transfer of carbon dioxide? (1)
the presence of the enzyme carbonic anhydrase inside red blood cells allows greater volumes of carbon dioxide to be transported. making it much more efficient
how else can carbon dioxide be transported? (1)
a much smaller amount of carbon dioxide can be combined directly with the amino groups of the polypeptide chains of haemoglobin inside red blood cells to form carbaminohaemoglobin.
what does haemoglobin do to prevent the blood from becoming too acidic? (1)
haemoglobin takes up H+ ions from the transport of carbon dioxide reactions.
