Blood oxygenation Flashcards
Components of blood
Plasma
RBC,WBC and platelets
Solutes: O2, CO2, glucose, amino acids
Erythrocytes
Red blood cells
Leucocytes
White blood cells
Haemoglobin structure
4°: 4 submits each made of
a polypeptide chain
a haem group contain a single Fe2+
How many O2 MOLECULES can each haemoglobin hold
4
How does haemoglobin bind O2
Fe2+ has an affinity to O2
Reaction of O22 being bound to haemoglobin
Hb + 4O2 > oxyhaemoglobin (Hb.4O2)
ppO2?
partial pressure of oxygen, measure of O2 conc. It is the pressure it would exert if it were the only gas in the atmosphere.
Where are haem groups found in haemoglobin and what does this mean
Center so it is difficult for O2 to bind as it must diffuse into the molecule
another term for ppO2 and units for both
oxygen tension (kPa)
Saturation of haemoglobin with O22 at low ppO2
low
What happens initially as ppO2 increases 2
Diffusion grad into haemoglobin increases
Eventually 1st O2 binds with a harm group changing the shape of the haemoglobin molecule making it easier for the 2nd to bind
Affect of the attachment of a 2nd O2 molecule to haemoglobin
induces another shape change
Does attachment of 3rd O2 molecule to haemoglobin induce a shape change
No
Under what conditions will a 4th O2 bind to haemoglobin
High ppO2, must be a large increase from the ppO2 when the third bound
Oxygen dissociation curve?
The relationship between levels of O2 in the TISSUES (ppO2) saturation of haemoglobin with O2 in the BLOOD
Main observations of oxygen dissociation curve 3
O2 affinity of Hb is high at high ppO2 and Hb doesnt release its O2
O2 affinity reduces as ppO2 reduces, O2 is readily released
Small decreases in ppO2 lead to alot of O2 dissociation from Hb
What is the shape of a curve showing cooperative binding of O2
sigmoid: s shaped
Shape of graph showing noncooperative O2 binding
more linear with plateau
Cooperative binding?
When the binding of a ligand to the first ligand site directly impacts the affinity of the second ligand site for that ligand
Noncooperative binding?
binding of a ligand doesn’t affect the affinity of the second ligand site for that ligand
What happens to oxyhaemoglobin at respiring tissues and why
The saturation of Hb is high
ppO2 of respiring tissue is low bc it is using up the O2 it has
Oxyhaemoglobin releases more O2 into the tissue
Affect of increasing conc of CO2 on oxyhaemoglobin
Oxyhaemoglobin releases O2 more readily meaning more O2 is available to respiring tissues when CO2 is being produced
Is 100% O2 saturation of haemoglobin typically reached, why?
No, it is very difficult for all haemoglobin molecules to become 100% saturated even at high oxygen tensions bc the binding of the 3rd molecule does not induce a shape change
Affect of increasing CO2 conc cooperative binding graph
Curve moves to the right: Bohr shift where a higher ppO2 yields a lower saturation of Hb than in lower concs of CO2
Benefit of Bohr effect for respiring cells and example
More O2 available when CO2 is produced e.g when exercising, muscles can be supplied with more O2 for continued respiration
What % of blood is plasma and what is cells
55% plasma
45% cells
What would be the issue if the O2 dissociation curve were linear
At high ppO2 Hbs affinity for O2 would be too low so O2 would be readily released and not reach respiring cells
At lower ppO2, Hbs affinity for O2 would be too high so O2 would not be released to respiring tissues
