Transport Of Oxygen By Haemoglobin Flashcards
Why’s the gradient of the oxygen dissociation curve shallow initially
Shape of haemoglobin molecule makes it difficult for the first oxygen molecule to bind to one of the sites on its four polypeptide subunits because they are closely united - therefore at low oxygen conc, little oxygen binds to haemoglobin
What does binding of the first oxygen molecule do in the oxygen dissociation curve
It changes the quaternary structure of the haemoglobin molecule, causing it to change shape, this change makes it easier for the other subunits to bind to an oxygen molecule
What’s positive cooperativity
It takes a smaller increase in partial pressure of oxygen to bind the second oxygen molecule then it did the first molecule. As binding of the first molecule makes binding of the second easier. The gradient curve steepens
Why does the gradient of the curve in the oxygen dissociation curve flatten off
It’s harder for the 4th molecule to bind, As with the majority of the binding sites occupied, it is less likely that a single oxygen molecule will find an empty site to bind to
If the oxygen dissociation curve is further to the left what does this mean
The greater the affinity of haemoglobin for oxygen ( so it loads oxygen result but unloads it less easily )
If the oxygen dissociation curve is further to the right what does this mean
The Lower the affinity of haemoglobin for oxygen ( so it loads oxygen less readily but unloads it more easily )
What effect does low co2 conc have on haemoglobin
At gas exchange surface, conc of co2 is low because it diffuses across the exchange surface and is excreted from the organism. The affinity of haemoglobin for oxygen is increased, and as conc of oxygen is high in lungs, means that oxygen is readily loaded by haemoglobin. The reduced co2 conc has shifted the curve to the left
What effect does high conc of co2 have on haemoglobin
In rapidly respiring tissues, the concentration of co2 is high. The affinity of haemoglobin for oxygen is reduced, which coupled with low concentration of oxygen in the muscles, means that oxygen is readily unloaded from the haemoglobin into the muscle cells. The increased carbon dioxide concentration has shifted the curve to the right
Describe the loading, transport and unloading of oxygen
At gas exchange surface co2 is being constantly removed
PH is slight raised due to low conc of co2
Higher pH changes shape of haemoglobin into one that enables it to load oxygen readily - also increases affinity of haemoglobin for oxygen, so it is not released while being transported in the blood to the tissues - in the tissues co2 is produced by respiring cells
Co2 is an acidic solution, so the pH of the blood within the tissues is lowered
Lower ph changes shape of haemoglobin into one with a lower affinity for oxygen
Haemoglobin releases its oxygen into the respiring tissues
How can we ensure that there is always sufficient oxygen for the repairing tissues
The higher rate of respiration - the more co2 the tissues produce - the Lower the pH - he greater the haemoglobin shape change - the more readily oxygen is unloaded - the the more oxygen is available for respiration
What’s the overall saturation of haemoglobin at atmospheric pressure ?
97%
