Transport of o2 Flashcards
Define partial pressure
pressure exerted by 1 of the gases in the mixture if it occupied that same volume on its own
What is on the x and y-axis of an oxygen dissociation curve?
x= partial pressure of o2/Kpa y= saturation of Hb (%)
Describe the shape of the oxygen dissociation curve
Initial shallow gradient
gradient of the curve steepens
gradient reduces graph flattens off
What is the usual o2 partial pressure?
21kpa
Describe how the HB molecule takes up oxygen
The shape of the HB molecules makes it hard for the first o2 molecules to bind as all the subunits are close together
binding of the first oxygen changes the 4 of the HB hence the shape so it is easier for other subunits to bind to an o2 molecules.
takes a smaller increase in the pp of o2 to bind the 2nd than 1st= positive cooperativity
after binding of the 3rd o2, due to probability, it is more difficult/less likely for a single o2 molecules will find an empty site to bind to
Why is it initially difficult for the Hb molecule to bind with oxygen?
The shape of the HB molecules as all the subunits are close together
When the graph is shifted to the right ____?
the affinity is lower
When the graph is shifted to the left ____?
the affinity is higher
What is the Bohr effect?
the greater the con. of CO2, the more readily the HB releases its oxygen. ( It reduces the affinity)
Describe the affinity to oxygen in the lungs
low con. of C02 / high con. O2
affinity increases
o2 readily loaded
reduced con. of co2 shifts curve to the left
Describe the affinity to oxygen in the respiring tissue
high con. of Co2 / lower con. o2
affinity decreases
o2 easily unloaded
increased co2 con shifted curve of the right
Why does the affinity to oxygen decrease in respiring tissues?
ph decreases as co2 is acidic in solution
low ph changes shape of HB
which lowers the affinity
Why does the affinity to oxygen increase in the lungs?
ph increased to low co2 con.
high ph changes shape of hb
so affinity increases
When answering the question what should you always mention?
higher/lower affinity
oxygen un/loaded more/less readily
Why is the affinity lower on tissue than lungs?
tissues have a higher rate of respiration more co2 produced lowers the pH greater the HB shape change more readily o2 is unloaded more o2 available 4 respiration
