Transport Of Carbon Dioxide And Oxygen Flashcards
What is one of the key roles of the mammalian transport system
Is to transport Oxygen and the vast majority of oxygen is transported by red blood cells in the blood.
What is another name for red blood cells
Erythrocytes
What are the adaptations of erythrocytes for transporting oxygen (1)
They have a biconcave structure giving them a large surface area to volume ratio, allowing oxygen to diffuse in and out rapidly.
What are the adaptations of erythrocytes for transporting oxygen (1)
Each Erythrocytes contains around 300 million molecules of haemoglobin
Erythrocytes don’t have a nucleus meaning that more of there volume is available to carry haemogblobin .
What can each of the groups in the haem molecule do
Each of the Fe2+ groups in the haem molecules can combine with one molecule of oxygen and as there are 4 haem groups in one molecule, one molecule of haemoglobin can combine with 4 molecules of oxygen.
What happens when haemoglobin binds with oxygen
It is now called oxyhaemoglobin
And it is reversible so oxyhaemoglobin can release the oxygen when required
Draw the equation for the binding of oxygen to haemoglobin
Hb + 4O2 <-> Hb(O2)4
What is an oxygen disassociation curve
A measurement of the amount of oxygen that combines with haemoglobin
On an oxygen disassociation curve what is on the y axis and x axis
On the y axis is the percentage saturation of haemoglobin with oxygen
On the x axis is the partial pressure of oxygen of O2
What does partial pressure mean
It is the concentration of oxygen however it is a gas so we say partial pressure.
What is the shape of the curve and therefore what is its name
The curve has an S shape so it is called a sigmoid curve
What occurs at low partial pressures of oxygen
Haemoglobin has a low affinity to oxygen
What is affinity
How strongly the haemoglobin is bound to the oxygen
What happens when one oxygen molecule binds to haemoglobin
Once one oxygen is bound the affinity of haemoglobin increases as it becomes much easier to bind to further oxygen molecules.
If there are no oxygen molecules bound what occurs
The haem groups have a low affinity for oxygen molecules. Which means that a relatively large partial pressure of oxygen is required for the first O2 molecule to bind to a haem group.
What occurs to the structure of haemoglobin when oxygen binds and what is this called
The quaternary structure changes increasing the affinity of the haem groups for oxygen.
This is called positive cooperativity.
What is a feature of the 4th oxygen molecule
It only binds to haem at a high partial pressures, as 3 of the 4 haem groups have been filled. So a chance of the oxygen colliding with the 4th is relatively low.
What is a feature of the partial pressure of oxygen in the alveoli
It is high and the haemoglobin in red blood cells is around 97% saturated.
What happens as red blood cells move into body tissues
However as red blood cells move into body tissues, the partial pressure of oxygen decreases as the tissues are carrying out aerobic respiration. And at a certain point one oxygen molecule unloads from the haemoglobin, changing its quaternary structure —> decreasing the oxygen affinity of the remaining haem groups.
What happens if the blood passes through very active tissue
Then the partial pressure of oxygen will fall even lower and because the haemoglobin has a reduced affinity for oxygen it is easier for more oxygen molecules to unload.
What does the oxygen disassociation curve look like
DRAW IT
What does aerobic respiration produce and what is the effect of its on the curve
It produces carbon dioxide, and the effect of this is to shift the whole oxygen dissociation curve to the right.
What is the Bohr effect
Carbon dioxide causes the oxygen affinity of haemoglobin to decrease - this is called the BOHR effect.
What is the first effect of the BOHR effect
Haemoglobin has a higher affinity for oxygen when partial pressures of carbon dioxide are low e.g in the lungs. So it has a high level of oxygen saturation there.
