TRANSPORT OF OXYGEN Flashcards
1
Q
what does hb (haemoglobin) do
A
- binds o2 in lungs and distributes in respiring tissues
2
Q
hb + o2 formula
A
4O2 + Hb = (reversible) Hb.4O2 (oxyhaemoglobin)
3
Q
What does hb need to do to transport O2 efficiently? (2)
A
- associate readily with O2 where gas exchange takes place (aveoli)
- dissociate readily at respiring tissues (muscles)
4
Q
how does hb fulfill contradictory requirements?
A
by changing its shape
5
Q
hb structure (2)
A
- four haem groups per hb
- each haem contains an Fe2+ ion
6
Q
cooperative binding (4)
A
- when the first o2 attaches it makes it easier for the second by changing hb’s shape
- when the second o2 attaches, it makes it easier for the third
- allows hb to pick up o2 rapidly in the lungs
- 3rd hb does not change shape so it takes a large increase in o2 partial pressure
7
Q
what shape is an o2 dissociation curve?
A
sigmoid
8
Q
how does partial pressure effect hb’s affinity to o2? (2)
A
- as pp increases so does affinity
- at very low pressures hb cannot bind with o2 easily
9
Q
how does fetal haemoglobin effect o2 d curves? (4)
A
- must absorb hb from maternal hb at placenta
- fetal hb has a higher affinity than mother’s at the same pp
- maternal/fetal blood flows close in placenta so o2 transfers to fetal hb
- it pushes the whole curve LEFT (increasing the pp at which it readily dissociates)
10
Q
lugworm (4)
A
- lives head-down in sand (low o2 environment)
- low metabolic rate
- so curve is left of normal humans
- hb loads o2 readily but only releases it at very low pps
11
Q
llama (4)
A
- at higher altitudes o2pp decreases
- llama’s o2 curve is to the left of normal humans
- loads o2 more readily in all pressures, release when o2 pp is low
12
Q
Bohr effect (3)
A
- when co2 conc, increases hb releases o2 more readily
- curve moves to the right at low pp of co2
- so in high co2 pp hb has a lower affinity for o2 (more efficient at unloading)
