transport of gases in blood Flashcards
what is the structure of haemoglobin ?
- four polypeptide chains, each bound to one haem group
- each haem group can combine with one oxygen molecule
- can combine with a maximum of 4 oxygen molecules - oxyhaemoglobin
what type of structure does haemoglobin have ?
quaternary structure
what is the Bohr effect ?
- when a high CO2 conc causes the oxyhaemoglobin curve to shift to the right
- the affinity for oxygen decreases bc the acidic C02 changes the shape of haemoglobin slightly
what happens if there is low partial pressure of carbon dioxide in the alveoli ? - Bohr effect
curve shifts to the left, increased affinity and therefore uploads more oxygen
what happens if there is high partial pressure of carbon dioxide at respiring tissues ? - Bohr effect
curve shifts to the right, decreased affinity and therefore unloads more oxygen
what happens to the curve of a dove ?
faster metabolism, so needs more oxygen for respiration to provide energy for contracting muscles
what happens to the curve of an earthworm ?
underground there is lower partial pressure of oxygen
oxyhaemoglobin dissociation curve
oxygen is loaded in regions with a high partial pressure of oxygen and is unloaded in regions of low partial pressure of oxygen
gas exchange surface e.g. alveoli
oxygen conc:
carbon dioxide conc:
affinity of haemoglobin for oxygen:
result:
oxygen conc: high
carbon dioxide conc: low
affinity of haemoglobin for oxygen: high
result: oxygen is attached - loads
respiring tissues
oxygen conc:
carbon dioxide conc:
affinity of haemoglobin for oxygen:
result:
oxygen conc: low
carbon dioxide conc: high
affinity of haemoglobin for oxygen: low
result: oxygen is released - unloads
affinity of haemoglobin for oxygen - define
readily associates (binds) with oxygen at the surface where gas exchange takes place (high PO2)
saturation of haemoglobin with oxygen - define
when haemoglobin is holding maximum of oxygen it can bind
what is loading ?
when the first oxygen molecule binds to the haem group and distorts shape of the whole molecule and so the other 3 molecules is taken up at increasing rate
what is unloading ?
- the opposite happens
the oxygen detaches and unbinds from haemoglobin
cooperative binding
haemoglobin changes shape when first oxygen binds making it easier for further oxygen
explain why the curves are S - shaped ?
this is called a sigmoid
if the curve shifts to the right, low affinity
if the curve shifts to the left, high affinity
why is it that when the greater the conc of CO2, more readily haemoglobin released oxygen ?
dissolved CO2 is acidic and the low pH causes haemoglobin to change shape so making it more likely to give up its oxygen
how does CO2 end up to the cells ? - haemoglobin
mammals respire releasing CO2 and H20 as a waste product
the carbon in CO2 binds to the hydrogen = carbonic acid this decreased the pH
an increase in oxygen levels = equilibrium into the cells why ? - haemoglobin changes shape - O2 unload
what does the increase in oxygen levels cause the Bohr shift to do ?
sigmoid shifts to the right
myoglobin
found in muscle cells and ensures that the high oxygen demand of muscles is met
one subunit so there is no cooperative binding
curve
foetal haemoglobin
- the haemoglobin of a mammalian foetus has a high affinity for oxygen that that of adult haemoglobin
- this allows the foetal haemoglobin to pick up oxygen from an environment that would normally cause adult
haemoglobin into release 02 - this causes the oxygen curve for the foetal haemoglobin to be the left to the curve for adult haemoglobin
