O2 and CO2 transport by M. Pandian

Introduction
Transport of O2 in the blood
Oxygen movement in the lungs and tissues
O2 dissociation curve
Bohr effect
Applied
Transport of CO2
The haldane effect
Chloride Shift or Hamburger Phenomenon
Reverse Chloride Shift

1. Tutorial
Pandian M
Department of Physiology
DYPMCKOP

2. Objectives
•Introduction
•Transport of O
2
in the blood
•Oxygen movement in the lungs and tissues
•O
2
dissociation curve
•Bohr effect
•Applied
•Transport of CO
2
•The haldane effect
•Chloride Shift or Hamburger Phenomenon
•Reverse Chloride Shift

3. Introduction
•Arterial pO
2
is ?
•Venous pO
2 is ?
•Arterial pO
2
is -
•98 – 100 mmHg
•Venous pO
2
is –
•40mmHg

4. Transport of O
2
in the blood
•Two form ?
A.In Dissolved form; and
B.In combination with Hb
•Amt of O
2
is 0.3ml/ 100 ml of blood per 100mmHg pO
2
•Each Hb molecule has 4 heme groups which have an iron in
ferrous form .
•Sixth valency bond of each Fe
2+
combines with 1 mole
(2atoms ) of O2.
•Therefore 4 moles (8 atoms) of O2 combine with one mole of
Hb

6. Transport of O
2
•The O
2
delivery system consists of Lungs, CVS,
Blood(Hb).
O
2
deliver to particular tissue is depends on :-
1.Amt of O
2
entering the lungs
2.Adequate of pulmonary gas exchanges
3.Capacity of the blood to carry O
2
4.Blood flow to the tissue
The O
2
delivery to tissue takes place in 3 steps:-
I.Up taking of O
2
by the blood in lungs
II.Transporting of O
2
in the blood
III.Delivery of O
2
to the tissues.

7. I. Up taking of O
2
by the blood in lungs
•This is mainly favored by O2 pressure gradient
Inspired Air is 150 mmHg.
Alveolar air is 104 mmHg.
Venous blood 40 mmHg.
•The pressure gradient fav the diffusion of O
2 from
the lungs into the venous blood.
•Its influenced by :-
a)Thickness of alveolocapillary memb
b)Area of the memb
c)Diffusion co-efficient of O
2

8. Thickness of alveolocapillary memb

9. •Applied :- Thickness of alveolocapillary memb
•Pulmonary fibrosis ↑ se the thickness less diffusion
•In lung collapse or uneven ventilation perfusion ratio of gas
exchanges are decreased
•Depends on the solubility & molecular weight of a gas
•Compared to Co
2
the solubility of O
2
in H
2
O is 20 times less.
•So diffusion rate of O
2
is less than Co
2.

10. •Under normal condition the blood becomes almost
saturated with O2 by the time it has passed through
one third of the pulmonary capillary,
• and little additional O
2
normally enters the blood
during the latter two thirds of its transit.
•That is, the blood normally stays in the lung
capillaries about three times as long as needed to
cause full oxygenation.
•Therefore, during exercise, even with a shortened
time of exposure in the capillaries,
• the blood can still become almost fully oxygenated.

12. Diffusion of oxygen from the peripheral capillaries into the
tissue fluid
•When the arterial blood reaches the peripheral tissues, its pO
2
in
the capillaries is still 95 mm Hg.
•the pO
2
in the interstitial fluid that surrounds the tissue cells
averages only 40 mm Hg.
•there is a large initial pressure difference that causes O
2
to diffuse
rapidly from the capillary blood into the tissues
•—so rapidly that the capillary pO
2
falls almost to equal the 40 mm
Hg pressure in the interstitium.
•So therefore, the pO
2
of the blood leaving the tissue capillaries
•and entering the systemic veins is also about 40 mm Hg

14. Diffusion of carbon dioxide from peripheral tissue cells into
the capillaries and from the
pulmonary capillaries into alveoli
•When O
2
is used by the cells, virtually all of it becomes Co
2
,
and this transformation increases the intracellular pCo
2
;
•because of this elevated tissue cell pCo
2
, Co
2
diffuses from
the cells into the capillaries and
• is then carried by the blood to the lungs.
• In the lungs, it diffuses from the pulmonary capillaries into
the alveoli and is expired.
•CO2 can diffuse about 20 times as rapidly as O2.

15. Oxygen movement in the lungs and tissues

16. O
2
dissociation curve
•Normally, Oxygen-hemoglobin dissociation
curve is ‘S’ shaped or sigmoid shaped.
•The curve that demonstrates the relationship
between partial pressure of oxygen and
•The percentage saturation of hemoglobin with
oxygen.
•It explains hemoglobin’s affinity for oxygen.

17. •Normally in the blood, hemoglobin is saturated
with oxygen only up to 95%.
•Saturation of hemoglobin with oxygen depends
upon the partial pressure of oxygen.
•When the partial pressure of oxygen is more,
hemoglobin accepts oxygen and
•when the partial pressure of oxygen is less,
hemoglobin releases oxygen

18. •P
50
•P
50
is the partial pressure of oxygen at which
hemoglobin saturation with oxygen is 50%.
•When the partial pressure of oxygen is 25 to 27 mm
Hg, the hemoglobin is saturated to about 50%.
•That is, the blood contains 50% of oxygen.
•At 40 mm Hg of partial pressure of oxygen, the
saturation is 75%.
•It becomes 95% when the partial pressure of oxygen
is 100 mm Hg.

19. O
2
dissociation curve

20. Factors Affecting Oxygen-hemoglobin
Dissociation Curve
Oxygen-hemoglobin dissociation curve is shifted to
left or right by various factors:
1. Shift to left indicates acceptance (association) of
oxygen by hemoglobin
2. Shift to right indicates dissociation of oxygen from
hemoglobin.

21. 1.SHIFT to right
•Oxy-heme. dissociation curve is shifted to right in the
following conditions:
i. Decrease in partial pressure of oxygen
ii. Increase in partial pressure of carbon dioxide (Bohr effect)
iii. Increase in hydrogen ion concentration and decrease in pH
(acidity)
iv. Increased body temperature
v. Excess of 2,3-diphosphoglycerate (DPG) in RBC. It is also
called 2,3-biphosphoglycerate (BPG).
DPG is a byproduct in Embden-Meyerhof pathway of
carbohydrate metabolism.
It combines with β-chains of hemoglobin. In conditions like
muscular exercise and in high attitude, the DPG increases in
RBC.
So, the oxygenhemoglobin dissociation curve shifts to right to
a great extent.

22. 2. Shift to left
Oxygen-hemoglobin dissociation curve is shifted to
left in the following conditions:
i. In fetal blood because, fetal hemoglobin has got
more affinity for oxygen than the adult hemoglobin
ii. Decrease in hydrogen ion concentration and
increase in pH (alkalinity).
iii. CO
iv. Myoglobin
v. Decreased in body temp.

24. Bohr Effect
•Bohr effect is the effect by which presence of CO
2

decreases the affinity of hemoglobin for oxygen.
(Christian Bohr in 1904.)
•In the tissues, due to continuous metabolic activities,
the partial pressure of CO
2
is very high and the
partial pressure of oxygen is low.
•Due to this pressure gradient, CO
2
enters the blood
and oxygen is released from the blood to the tissues.
•Presence of CO
2
decreases the affinity of
hemoglobin for oxygen.
• It enhances further release of oxygen to the tissues
and oxygendissociation curve is shifted to right.

25. TRANSPORT OF CARBON DIOXIDE
IN THE BLOOD
•Carbon dioxide is transported by the blood from cells to
the alveoli.
•Recall that the PCO2 of venous blood is 45 mm Hg and
that of arterial blood is 40 mm Hg.
•For 45 mm Hg is about 2.7 ml/dl
•Amt dissolved at 40 mm Hg is about 2.4 milliliters, or a
difference of 0.3 milliliter.
•This is about 7 percent of all the CO2 normally
transported.

26. Reaction of Carbon Dioxide with Water in the Red
Blood Cells—Effect of Carbonic Anhydrase

27. THE HALDANE EFFECT
•Earlier we pointed out that an increase in Co
2
in the
blood causes O
2
to be displaced from the
hemoglobin (the Bohr effect),
•which is an important factor in increasing O
2

transport. The reverse is also true:
• binding of O
2
with hemoglobin tends to displace Co
2

from the blood.
• Indeed, this effect, called the Haldane effect, is
quantitatively far more important in promoting Co
2

transport than is the Bohr effect in promoting O
2
transport.

28. Chloride Shift or Hamburger Phenomenon

29. Reverse Chloride Shift

30. Summary of CO2 movement.

31. References
•Text book of Medical Physiology
– Guyton & Hall
•Human Physiology
–Vander
•Net source

32. THANK YOU . THANK YOU .
. .. .