oxygen and carbon dioxide transport Flashcards
how does haemoglobin function as a useful respiratory pigment
picks up O2 in areas w/high ppO and releases O2 where there is a low ppO
what type of protien is hamoglobin
globular, conjugated
state the prosthetic group in haemoglobin
haem group which is an iron(II) ion
how many haem groups does Hb have
4
how many O2 molecules can Hb carry
4
where do O2 molecules bind to in Hb
haem groups
what is formed when Hb and O2 combine
oxyhaemoglobin
what is the equation for the formation of oxyhaemoglobin
Hb+4O2->HbO8
reversible
what is meant by the terms loading and unloading
Hb binding with ox
Hb relasing ox
what does Hb’s affinity depend
p(O2)
what does Hb’s affinity depend on
p(O2)
effect of ox conc on affinity
high ox conc= high p(O2)=high afinity
low ox conc= low ppO= low affinity
when the frst ox binds does it make it easier/ harder for other ox to bind
easier
why is it difficult for ox to load onto haem groups at low ppO
polypeptide chains tightly bound
when the frst ox binds does it make it easier/ harder for other ox to bind
easier- positve cooperativity
what causes the ox diss curve to rise steeply
after 1 ox binds polypeptide chain opens exposing other 3 groups
why does the ox dis curve level of at high ppO
Hb is saturated
what has a higher aff for ox fetal/ adult Hb
fetal
importance of fetal Hb having a higher ox aff
fetus needs ox from mother’s blood, ppO low in placenta, adult Hb needs to unload and fetal Hb needs to load, maintains conc grad across placenta
where is the postioning of fetal cuvre cmpared to the adult cruve
to the left
biconcave shape
larger surface area for gaseous exchange, pass through narrow capillaries
why do erythroctes have a limited life
no nucleus/ mitochindra
what is Hb composed of
4 peptide chains
where are there relatively low ox levels
capillaries in the lungs
what is there bw inside of Hb and air in alveoli
steep conc gradient- ox
how is a steep concentarion gradent maintained in erythrocyte
ox bound to Hb so free ox conc in erythrocyte stays low
what is rel ox con in cyto of body cells compared to in RBCs
lower in body cells
describe unloading
ox moves out of RBC down conc grad, after 1 released Hb changes shape so easier for other ox to be released
what are axis of ox diss curve
% saturation of Hb in blood plotted against ppO
what does ox diss graph show
% saturation of Hb in blood plotted against ppO
where is myoglobin found
muscles
explain diff bw Hb and myoglobin
myoglobin has a much higher aff for ox so muscles can take ox from Hb in blood, enabling muscles to get extra ox when contracting during exercise
when is myoglobin used
when the amount of ox falls
what happens to the overall pa of air as altitude increases
decreases, proportions stay the same
what is meant by ppO
rel conc of ox compared to other gases
why does a little change in ppO make a sig diff to saturation of Hb w/O2
once first mol att the change in shape means other ox mols added rapidly
where does rapid loading occur
lungs- bc low ppO
what happens when resp cells a a small drop in ox levels. how is the eff enhanced
ox rel rapidly from Hb to diffuse into cells
enhanced by rel low pH in tissues comp to lungs
importance of Bohr effect in lungs
rel low ppCO2 so ox binds to Hb easily
what happens to curve when co2 conc inc
shifts right- Bohr shift
imp of bohr effect in active tissues
have high ppCO2 sp Hb gives up its ox more easily
what would be the case if fetal and adult Hb had the same afff for ox
little or no ox tranfered to fetal blood as no conc grad established
how is co2 transported from tissues to lungs
plasma
carbominoHb
(mostly) hydrogen carbonate ions in cyto of RBCs
how is carbominhaemoglobin formed
co2 comines w/ a.a groups in pp chains of Hb
co2 reacts slowly with water to form
carbonic acid-H2CO-
what does carbonic acid dissociate to form
hydrogen ion and and hydrogen carbonate ion- HCO3-
name and functions of enzyme inv in formation of carbonic acid
carbonic anhydrase
catalyses the rversible reaction bw co2 and water
what type of reation is the formation and diss of carbonic acid
reversible
descirbe process of hydrogen carbonate leaving the Hb
diffuses out of RBC, down conc grad
describe chloride shift
as negative HCO3- diff out, Cl- diff into RBC
purpose of chloride shift
to maintain the electrical balance of the RBC
what does removing and converting co2 into HCO3-s do
maintains steep conc grad for co2 to diffuse from the respiring tissues into RBCs
describe what happens to carbonic acid when blood reaches lungs tissue
carbonic acid catalyses the reverse reaction- b.down c.acid into co2 and water
describe what happens to cl- when blood reaches lungs
diff out of RBC down electrochemical gradient
describe what happens to HCO3- when blood reaches lungs
diff back into RBC and react w/ H+ to form more c.acid
descibe the role of Hb when blood reaches lungs
acts as a buffer- prevents changes in pH by accepting free H+ in a reversible reaction to form haemoglobinic acid
how is haemoglobinic acid formed
when Hb accepts free H+s
how is the absence of nucei in mature RBCs an adaptation
allows more room for maximum amount of Hb
how is the presence of Hb in RBCs an adaptation
able to carry oxygen
how is the enzyme carbonic anhydrase an adaptation of RBCs
inv in carriage of co2 in blood
show diff in myoglobin and Hb curve
.
show diff bw fetal and adult Hb curves
.
use flow chart to summarise how co2 prod in cells is carried to lungs in RBCs
clearly shw main stages of co2 transport
x incl plasma transport as spec states RBCs
