This document summarizes the transport of oxygen in the body. Oxygen is taken up from the lungs where the alveolar PO2 is 104 mmHg into pulmonary blood where it drops to 95 mmHg. It is transported primarily bound to hemoglobin in red blood cells but also dissolved in plasma. The oxygen-hemoglobin dissociation curve is sigmoid shaped which allows for efficient uptake and unloading in tissues where PO2 is around 40 mmHg. Factors like pH, PCO2, temperature and 2,3-DPG can shift the curve right or left modifying hemoglobin's affinity for oxygen. Myoglobin also transports oxygen in muscle tissue.

1. Dept. Of physiology
BDS 1st ; 17th June 2020
TRANSPORT OF
OXYGEN

2. OBJECTIVES
Uptakeofoxygenbypulmonary blood.
Transportofoxygeninarterial blood.
Releaseofoxygenin tissue.
Vehiclefortransportof oxygen.

3. INTRODUCTION
Transport of gases occurs along the
conc gradient.
AlveolarairPO2:104 mmHg.
ArterialbloodPO2:95mmHg
VenousbloodPO2:40mmHg.
Tissueinterstitialfluid:40 mmHg.

4. UPTAKE OF OXYGEN BY
PULMONARY BLOOD.
AlveolarPO2-104 mm
Hg.
Arterialblood po2 40 mm
Hg.
Conc gradient of 64 mm
Hg,transport is rapid.

5. TRANSPORT OF OXYGEN IN
ARTERIAL BLOOD.
PO2 in pulmonary veins 104
mmHg& in aorta 100mmHg.
Due to venous
admixture
Bronchial veins mix with
pulmonary capillaries
Coronary blood through
Thebesian Veins.

6. TRANSPORT OF OXYGEN IN
ARTERIAL BLOOD.
Dissolvedform
Incombinationwith
haemoglobin.
Oxygen inArterial blood –
20ml/100ml,in venous blood
15ml/100ml
So 5ml/100 ml transported
from lungs to tissue.

7. DISSOLVED FORM
Out of 5 ml transported 0.3ml in
dissolved form & rest with Hb.
As per Henry’s law dissolved gas
is proportional to Po2, so there is
NOLIMITfor this transport as long
as Po2 is high.
So dissolved O2 at high Po2
( HyperbaricOxygen)is used for
oxygenation in certain poisoning
(CO)where Hbis denatured.

8. IN COMBINATION WITH
HAEMOGLOBIN.
Oxygenation of haemoglobin
Oxygen carrying capacity of haemoglobin
O2-Hbdissociation curve.
Shifts in O2-Hbdissociation curve.
Concept of P50 & its significance.
O2-Hbdissociation curve of Hb-F
Effect of carbon monoxide on tranport of O2
Oxygen dissociation curve for myoglobin.

9. OXYGENATION OF
HAEMOGLOBIN
Oxygen combine with Hbto
form loose & reversible
bond, this is oxygenation&
Not Oxidation,convert
Deoxyhaemoglobin into
Oxyhaemoglobin.
Time taken 0.1 sec.

10. OXYGEN CARRYING CAPACITY
OF HAEMOGLOBIN
1 gm of Hbbindwith
1.34mlofO2
100 ml blood containingHb
15gm% (15Χ 1.34)bind
20.1 mlof O2
But due to different shunts
decreases to 19.8 mlout of
which 0.3ml in dissolved form
& 19.5 mlas Oxyhemoglobin.

11. DISADVANTAGE
Only Disadvantage with this
method is there is Ceiling
with this transport due toHb
saturation.
% Saturationis Avg
saturation of entire Hb
molecule in the blood.

12. O2-HB DISSOCIATION CURVE
When relation between PO2
& % of Hbsaturation is
plotted on graph we get
OXYGEN-
HAEMOGLOBIN
DISSOCIATION CURVE.
It shows that % of Hb
saturation increases with
increase in PO2,but this
relationship is notlinear

13. SIGMOID SHAPED CURVE -
CAUSE
When 1 molecule of O2
combines with Hb, affinityof
Hbincreases & so on
This is called Co-
operativebinding
Kinetics.
Due to this O2-Hb
dissociation curve is
Sigmoid.

14. SIGMOID SHAPED CURVE -
Advantage
Loading Zone – Related to
process of O2 uptake in
lungs.
Even Po2 falls below
60 mmHgsaturation
is still 90%, so
loading zone provide
margin of safety.

15. SIGMOID SHAPED CURVE -
Advantage
Unloadingzone–related to
O2delivery in tissue,
steep portion below Po2
60mmHg.
So that relatively large
Oxygen is liberated at
minor fall in o2 tension. (
BufferingEffect)

16. SHIFTS IN O2-HB
DISSOCIATION CURVE.
Shiftto Right
-Decreased affinity of
Hbfor O2.
Causes
PCO2& pH–Increase in
Pco2 shift curve to Right
–Bohr’s effect.

17. SHIFTS IN O2-HB
DISSOCIATION CURVE.
Temperature–increase
temperature is due to increase heat
production, increased PCo2 due to
rapid metabolism, decreased PO2
due to rapid consumption &
decreased pH due to lactic acid
accumulation.
2,3-Diphosphoglycerate–formed
during Glycolysis via
EMBEDEN-MEYERHOF
pathway.

18. SHIFTS IN O2-HB
DISSOCIATION CURVE.
Shifttoleft–increase affinity
of haemoglobin for oxygen.
Causes–
Pco2
H+ionconc
Temperature
Fetal haemoglobin

19. CONCEPT OF P50 & ITS
SIGNIFICANCE.
P50–partial pressure of oxygen that produces 50% of
saturation
NormalP50–25-27 mmHg.
Significance–Hbaffinity inversely proportional to P50
value.
Decreased p50 –Hbgets saturated at low po2, i.e
shift to left
Increased p50 - Hbgets saturated at high po2, i.e
shift to right.

20. O2-HBDISSOCIATIONCURVEOFHB-F
O2-Hbdissociation curve
shifted to Left
As its affinityfor 2,3- DPG
is lessthanHbA
So its affinityto combine
with oxygen is morethan
HbA.

21. EFFECT OF CARBON MONOXIDE
ON TRANSPORT OF O2
CO has 200 more
affinity for Hb.
Combines with Hb forms-
Carboxyhaemoglobin
Decreases functional Hb
conc.
And decreases O2 tension
& O2 transport.

22. OXYGEN DISSOCIATION CURVE
FOR MYOGLOBIN.
Present in Musclespecialised
for sustained contraction
Dissociation curve is
RectangularHyperbola–as it
takes O2 at low pressure
readily
It does not show Bohr’s effect
At po2 40 mmHgit is 95%
saturated & Hb75%
Act as temporary storehouse
of Oxygen

23. RELEASE OF OXYGEN IN
TISSUE.
O2 release at Rest
O2 release during
exercise.

24. O2 RELEASE AT REST
OxygenDelivery–Normal o2 delivery is 1L/min
OxygenConsumption–5ml/100ml/min, so total is 250 ml/min
UtilizationCoefficient- % of O2consumed out of oxygen
delivered to tissue.
250/1000×100 =25%

25. O2 RELEASE DURING
EXERCISE.
Depend on Severityof
exercise
Deliveryofoxygen–
increased by
Increase blood flow due to
increase cardiac output, local
arteriole dilatation, increase in
open capillaries.
Increase RBCcount due to
splenic contraction
Releaseofoxygen–by
right sift of curve.

26. VEHICLE FOR TRANSPORT OF
OXYGEN.
AtPO2100mmHg
Whole blood –19.8ml
Hbsoln –19.5 ml
plasma soln –0.3 ml
AtPO240mmHg
Whole blood –5 ml
Hbsoln –1.5 ml
plasma soln –0.18 ml