transport of oxygen Flashcards
what is the partial pressure of oxygen
-the measure of oxygen concentration (pO2)
what does a higher partial pressure mean
a greater concentration of dissolved O2 in cells
what varies depending on partial pressure
haemaglobins affinity for oxygen
describe haemaglobins affinity for O2 at a high partial pressure
-higher affinity so oxygen associates with haemaglobin
describe haemaglobins affinity for O2 at a low partial pressure
-less affinity as there is a lower partial pressure
what happens when cells respire
-they use up the oxygen which lowers the partial pressure
-oxygen dissociates from haemaglobin
what is the role of the haem group
-has a high affinity for oxygen
-only 1 oxygen molecule can be associated for each so only 4 oxygen molecules in total
where is oxygen absorbed into
-the plasma (blood) as it passes the alveoli in the lungs
where does the oxygen enter
into an erthryocyte
what allows more oxygen to enter the blood from the lungs
the steep concentration gradient after oxygen is taken out of solution
what 2 things work together so that oxygen can be transported
-the partial pressure gradient
-conformational change
-the cooperactivity of these two
what can be used to show what happens to the percentage saturation of haemaglobin oxygen as the partial pressure of oxygen increases
-the haemaglobin dissociation curve
describe and explain the first section of the haemaglobin dissociation curve
-low oxygen tension- haemaglobin wont readily bind to o2
-difficulty in combining with the first oxygen molecule accounts for low o2 tensions
why is it that haemaglobin wont readily bind to o2 at low oxygen affinity
-because the haem group that attracts the oxygen is in the centre of the haemaglobin molecule making it difficult for the oxygen to reach the first o2 molecule
what happens at the second stage of the heamaglobin dissociation curve
-the oxygen tension rises
-diffusion gradient into haemaglobin rises
-one oxygen molecule enters haemaglobin molecule and associates causing conformational change
why is the curve so steep at the second stage
-because when one o2 molecule joins, it causes a conformational change which makes it easier for others to associate
what does the predicted straight line on a haemaglobin dissociation curve show
-for a normal liquid
-expect conc of 02 absorbed into liquid to be directly proportional to oxygen tension in air
