This document summarizes the mechanisms of oxygen and carbon dioxide transportation in the body. It explains that oxygen is transported primarily bound to hemoglobin in red blood cells (98.5%), while carbon dioxide is transported through dissolved, chemically bound, and bicarbonate ion forms. Key aspects covered include cooperative binding of oxygen to hemoglobin, the oxygen dissociation curve, and factors like pH, temperature, and carbon dioxide levels that affect oxygen unloading from hemoglobin in tissues. The roles of carbonic acid, bicarbonate ions, and carbaminohemoglobin in carbon dioxide transport are also described, as well as the interacting Bohr and Haldane effects.

3. Ω To explain the mechanism of
transportation of Oxygen &
Carbon Di-oxide in the body.

4. OUTLINE
o To explore how O2 is transported in
the blood.
o To explore how Co2 is transported in
the blood.
o This will include understanding the
Oxygen & Carbon Di-oxide dissociation
curve.

6. Oxygen Transport
Method Percentage
Dissolved in Plasma 1.5 %
Combined with Hemoglobin 98.5 %

7. Oxygen Transport

8. Oxygen Transport
Bound to Hgb
Dissolved

9. Oxygen Transport
Haemoglobin molecules can
transport up to four O2’s
When 4 O2’s are bound to haemoglobin,
it is 100% saturated, with fewer O2’s it is
partially saturated.
Oxygen binding occurs in response
to the high partial pressure of
Oxygen in the lungs
Co-operative binding:
haemoglobin’s affinity for O2
increases as its saturation
increases.

10. Oxygen Transport
Oxyhemoglobin Formation:
Oxygen + Hb  Oxyhemoglobin (Reversible)
• In the lungs w her e the par tial pr es s ur e of oxygen
is high, the r xn pr oc eeds to the r ight for ming
Oxyhemoglobin
• W hen oxygen binds to haemoglobin, it for ms
OXYH AEMOGLOBIN .
• In the tis s ues where the partial pres s ure of
oxygen is low, the r xn r ever s es. OxyH b w ill
r eleas e oxygen, for ming again H b ( or pr oper ly
s aid deoxyhemoglobin )

11. 11
Oxygen Capacity: The maximum quantity of oxygen that will
combine chemically with the hemoglobin in a unit volume of blood
Normal Value: 1.34 ml of O2 per gm of Hb or 20 ml of O2 per 100 ml of
blood.
Oxygen Content: how much oxygen is in the blood
Oxygen Saturation : The percentage of all the available heme
binding sites saturated with oxygen
Basic Concepts:

12. T h e o x y g e n - h e m o g l o b i n
d i s s o c i a t i o n c u r v e :
Haemoglobin saturation is
determined by the partial pressure of
oxygen. When these values are
graphed they produce the Oxygen
Disassociation Curve
In the lungs the partial
pressure is approximately
100mm Hg at this Partial
Pressure haemoglobin has
a high affinity to 02 and is
98% saturated.
In the tissues of other
organs a typical PO2 is 40
mmHg here haemoglobin
has a lower affinity for O2
and releases some but not
all of its O2 to the tissues.
When haemoglobin leaves
the tissues it is still 75%
saturated.

13. T h e o x y g e n - h e m o g l o b i n
d i s s o c i a t i o n c u r v e :
Haemoglobin Saturation at High Values
Lungs at sea level: PO2
of 100mmHg
haemoglobin is 98%
SATURATED
Lungs at high
elevations: PO2 of
80mmHg,
haemoglobin 95
% saturated
Even though PO2
differs by 20 mmHg
there is almost no
difference in
haemoglobin
saturation.
When the PO2 in the lungs
declines below typical sea
level values, haemoglobin
still has a high affinity for
O2 and remains almost
fully saturated.

14. T h e o x y g e n - h e m o g l o b i n
d i s s o c i a t i o n c u r v e :

15. Factors Affecting Haemoglobin
Saturation

16. Factors affecting
Disassociation
B L O O D
T E M P E R A T U R E
• increased blood temperature
• reduces haemoglobin affinity for O2
• hence more O2 is delivered to warmed-
up tissue

17. B L O O D P h
• lowering of blood pH (making blood
more acidic)
• caused by presence of H+ ions from
lactic acid or carbonic acid
• reduces affinity of Hb for O2
• and more O2 is delivered to acidic
sites which are working harder
Factors affecting
Disassociation

18. C A R B O N D I O X I D E
C O N C E N T R A T I O N
• The higher CO2 concentration in tissue
• The less the affinity of Hb for O2
• So the harder the tissue is working, the more O2
is released
Factors affecting
Disassociation

19. Bohr Effect
• Bohr Effect refers to the
changes in the affinity of
Hemoglobin for oxygen.
• It is represented by shifts
in the Hb-O2 dissociation
curve
• Three curves are shown with
progressively decreasing
oxygen affinity indicated by
increasing P(50)

20. SHIFT to the RIGHT
Decreased affinity of Hb for Oxygen
Increased delivery of Oxygen to tissues
It is brought about by
1. Increased partial pressure of Carbon Dioxide
2. Lower pH (high [H+])
3. Increased temperature
Ex: increased physical activity, high body
temperature (hot weather as well), tissue
hypoxia (lack of O2 in tissues)

22. • SHIFT to the LEFT
• Increased affinity of Hb for Oxygen
• Decreased delivery of Oxygen to tissues
• It is brought about by
1. Decreased partial pressure of Carbon Dioxide
2. Higher pH (low [H+])
3. Decreased temperature
• Ex: decreased physical activity, low body
temperature (cold weather as well),
satisfactory tissue oxygenation

24. Key Point
• Increased temperature and hydrogen ion (H+)
(pH) concentration in exercising muscle affect
the oxygen dissociation curve, allowing more
oxygen to be uploaded to supply the active
muscles.

25. Carbon Dioxide Transport
Method Percentage
• Dissolved in Plasma 7 - 10 %
• Chemically Bound to
Hemoglobin in RBC’s 20 - 30 %
• As Bicarbonate Ion in
Plasma 60 -70 %

26. Dissolved
bound to Hb
HCO3-
Carbon Dioxide Transport

27. Carbon Dioxide Transport
Carbaminohemoglobin Formation
• Carbon dioxide molecule reversibly attaches to
an amino portion of hemoglobin.
CO2 + Hb HbCO2

28. Carbon Dioxide Transport
Carbonic Acid Formation
• The carbonic anhydrase stimulates water to
combine quickly with carbon dioxide.
CO2 + H2 0 H2 CO3

29. Carbon Dioxide Transport
Bicarbonate Ion Formation
• Carbonic acid breaks down to release a hydrogen
ion and bicarbonate.
H2 CO3 H+ + HCO-
3

30. 3030
CO2 Transport and Cl- Movement

31. •
This shifts the oxygen-haemoglobin dissociation curve to the right.
Thus formation of bicarbonate ion enhances oxygen uploading.
Bicarbonate Ions
This also plays a buffering as the H+ is neutralised therefore preventing any acidification of the
blood.
When blood enters the lungs, where the PCO2 is lower, the H+ and bicarbonate ions rejoin to
form carbonic acid, which then splits into carbon dioxide and water.
In other words the carbon dioxide is re-formed and can enter the alveoli and then be exhaled.
Key Point
The majority of carbon dioxide produced by the active muscles is transported back to the lungs
in the form of bicarbonate ions.
Carbaminohaemoglobin
CO2 transport also can occur when the gas binds with haemoglobin, forming a compound called
Carbaminohaemoglobin.
It is named so because CO2binds with the amino acids in the globin part of the haemoglobin,
rather than the haeme group oxygen does.
EXTRA

32. •
The dissolved carbon dioxide comes out of solution where the PCO2 is low, such as in the lungs.
There it diffuses out of the capillaries into the alveoli to be exhaled.
Bicarbonate Ions
Bicarbonate Ions
Carbon Dioxide and water molecules combine to form carbonic acid (H2CO3).
This acid is unstable and quickly dissociates, freeing a hydrogen ion (H+) and forming a
bicarbonate ion (HCO3-):
CO2 + H2O H2CO3 CO2 + H2O
Bicarbonate Ions
The H+ subsequently binds to haemoglobin and this binding triggers the BOHR effect (mentioned
earlier).
EXTRA

33. Carbon Dioxide Dissociation
Curve
Haldane effect
For any given PCO2, the
blood will hold more
CO2 when the PO2 has
been diminished.
Reflects the tendency
for an increase in PO2 to
diminish the affinity of
hemoglobin for CO2.

34. Mechanism of Haldane effect
Combination of oxygen with hemoglobin in the lungs cause
the hemoglobin to becomes a stronger acid. Therefore:
1) The more highly acidic hemoglobin has less tendency to
combine with CO2 to form CO2 Hb
2) The increased acidity of the hemoglobin also causes it to
release an excess of hydrogen irons.

35. Interaction Between CO2 and O2
Transportation
1. Bohr effect

36. 2. Haldane effect