Haemoglobin Flashcards
Haemoglobin is…
a globular protein which transports oxygen around the body.
The equation of oxyhaemoglobin:
Hb + 4O2 = Hb08
Haemoglobin needs to be able to…
pick up the oxygen at the lungs and release it when it reaches a tissue.
If a sample of blood is saturated, it means…
that it contains the maximum amount of oxygen it can possibly have.
Dissociation curve shows…
the relationship between percentage saturation of a sample and the partial pressure of oxygen. It is a S-shaped graph.
To investigate how haemoglobin behaves, samples of…
blood are exposed to different partial pressures of oxygen.
The amount of oxygen which combines with the sample is then…
measured.
The haemoglobin dissociation curve shows a trend that…
at a low partial pressure of oxygen, the percentage saturation is very low. As the partial pressure increases, the saturation increases as well.
The partial pressure of oxygen in the lungs is…
very high, therefore, the saturation of haemoglobin is very high (95-97%).
The partial pressure of oxygen in an actively respiring muscle is…
very low, so the saturation of haemoglobin would be low too (20-25%).
When oxygen combines with one haem group…
the whole haemoglobin becomes slightly distorted. This causes that next molecule of oxygen binds more affinitatively to the next haem group.
The S-shape of the dissociation curve is caused by…
increased affinity of haemoglobin to combine with oxygen after the first oxygen molecule.
The haemoglobin dissociation curve is also affected by…
the partial pressure of CO2.
Some of the CO2 in blood plasma diffuses into…
the red blood cells.
Carbonic anhydrase is…
an enzyme found in the cytoplasm of the red blood cells.
Carbonic anhydrase catalysis…
the formation of carbonic acid. CO2 + H2O = H2CO3
The carbonic acid dissociates into…
H+ + hydrogenarbonate ion (HCO3-)
Haemoglobin combines with the hydrogen ions…
forming haemoglobinic acid(HHb), which releases the oxygen.
The haemoglobin acts as a buffer, since…
it removes hydrogen ions from the solution maintaining the right pH.
Bohr effect is that…
the presence of high partial pressure of CO2 causes haemoglobin to release oxygen.
The high CO2 concentrations in respiring muscles cause…
haemoglobin to release its oxygen even more rapidly than it would do due to a low partial pressure of O2
The CO2 is transported in the blood in 3 ways:
- by hydrogencarbonate ions
- some dissolves in blood plasma
- some form carbaminohaemoglobin
The hydrogencarbonate ions are formed…
in the cytoplasm of the red blood cell. Then they diffuse into the blood plasma. Around 85% of CO2 is carried this way.
Some CO2 dissolves in…
the blood plasma. Around 5% is transported this way.
Some CO2 molecules do not undergo the reaction catalysed by carbonic anhydrase, but…
combine directly with the terminal amine groups (-NH2) of the haemoglobin molecules. This forms carbaminohaemoglobin. 10% is transported this way.
When the blood reaches the lungs, the reaction used to transport CO2 go…
into reverse, as the concentration of CO2 is low.
Carbon monoxide combines with haemoglobin very…
readily and almost irreversibly.
Carbon monoxide is formed when…
carbon-containing compound burns incompletely.
CO combines with haem group of…
haemoglobin and forms carboxyhaemoglobin.
The affinity of haemoglobin for CO is…
250x higher than for O2.
Carboxyhaemoglobin is very…
stable compound, lasting very long.
CO causes death by…
asphyxiation.
At a hight of…
6500m, there is very low oxygen pressure.
In high altitudes, only…
70% of haemoglobin is saturated.
Altitude sickness is caused by…
rapid change in altitude, so the body does not have enough time to adjust(produce more red blood cells).
