23085077
Description
Mind Map by Joe Hitchings, updated more than 1 year ago
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Created by Joe Hitchings
almost 4 years ago
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|
8.4 Transport of oxygen in
the blood
- Role of
haemoglobin
- Oxygen bind to haemoglobin to
form oxyhaemoglobin
- In respiring tissue O2
dissociates from
oxyhaemoglobin
- O2 then diffuses out
of the erythrocytes
to respiring cells
- Haemoglobin can readily
associate with O2 when
there's are high conc of O2
and readily dissociate when
there's a low conc.
- Haemoglobin can readily
associate with O2 when
there's are high conc of O2
and readily dissociate when
there's a low conc.
- O2 then diffuses out
of the erythrocytes
to respiring cells
- In respiring tissue O2
dissociates from
oxyhaemoglobin
- Haemoglobin is comprised
of 4 sub-units ( 2 alpha
glucose, 2 beta glucose)
- Each sub-unit is comprised
of 1 polypeptide chain and 1
haem group with an iron
ion at the centre
- Each iron ion can
reversably bind to
O2
- The haem group has an affinity for O2
- Therefore O2 + haemoglobin = oxyhaemoglobin
is a reversable reaction
- The haem group has an affinity for O2
- Each iron ion can
reversably bind to
O2
- Each sub-unit is comprised
of 1 polypeptide chain and 1
haem group with an iron
ion at the centre
- Oxygen bind to haemoglobin to
form oxyhaemoglobin
- Loading O2
- Partial pressure = amount
of pressure exerted by a gas
relative to the total
pressure exerted by all the
gases in the mixture.
- Measured in KPa and written as P(x)
- Measured in KPa and written as P(x)
- How O2 is loaded
- Haemoglobin doesn't
absorb evenly
- At low conc's the sub-units are
tightly packed making it
difficult for the first O2 to bind.
- After the first
O2 has bound
there is a
conformational
change of the
haemoglobin -
making it
easier for the
2nd and 3rd
O2's to bind
- Then its
difficult for
the 4th O2 to
associate as
the
haemoglobin
molecule is
'full'
- Then its
difficult for
the 4th O2 to
associate as
the
haemoglobin
molecule is
'full'
- After the first
O2 has bound
there is a
conformational
change of the
haemoglobin -
making it
easier for the
2nd and 3rd
O2's to bind
- At low conc's the sub-units are
tightly packed making it
difficult for the first O2 to bind.
- Haemoglobin doesn't
absorb evenly
- Oxygen dissociation curve (Sigmoid curve)
- Tissues(low Kpa)
- P(O2) = 2-4 Kpa
- A small decrease in P(O2)
leads to a large decrease in %
saturation
- Haemoglobin has a low affinity for O2
- Haemoglobin has a low affinity for O2
- A small decrease in P(O2)
leads to a large decrease in %
saturation
- P(O2) = 2-4 Kpa
- Lungs (high KPa)
- P(O2) = 10-12 KPa
- A large decrease in P(O2) leads to
a small decrease in % saturation
- Haemoglobin has a high affinity for O2
- Haemoglobin has a high affinity for O2
- A large decrease in P(O2) leads to
a small decrease in % saturation
- P(O2) = 10-12 KPa
- Tissues(low Kpa)
- Remember to
read the graph
from right to
left
- Partial pressure = amount
of pressure exerted by a gas
relative to the total
pressure exerted by all the
gases in the mixture.
- Foetal
haemoglobin
- Blood arrives at the placenta, low P(O2) (2-4 Kpa)
- Haemoglobin has a low affinity for O2
- At this point foetal haemoglobin has
a higher affinity for O2
- The adult haemoglobin dissociates
with O2 releasing it to the placenta
tissue when it will readily associate
with foetal haemoglobin
- The adult haemoglobin dissociates
with O2 releasing it to the placenta
tissue when it will readily associate
with foetal haemoglobin
- At this point foetal haemoglobin has
a higher affinity for O2
- Haemoglobin has a low affinity for O2
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