1. TRANSPORT OF
RESPIRATORY
GASES

2. RESPIRATORY GASES; How are they transported in the blood???
CARBONDIOXIDE,
CO2
OXYGEN, O2
The only way for
Oxygen to be carried
around the body
is by the
HEAMOGLOBIN, in
red blood cells.
Carbondioxide is transported by
the blood in three ways;
A)As sodium hydrogencarbonate in plasma
B)As carbomino compounds in red
cells
C) In simple solution, dissolved in
the plasma

3. Transport of O2 by the Heamoglobin
Inside red blood cells, there are many heamoglobin molecules which are
large globular proteins, each consisting of two alpha subunits and two
beta subunits.
Each subunit has a haem group and a polypeptide globin, This globin molecule coils around the haem groups which contain iron.
The iron atom can reversibly bond with one molecule of oxygen. Since
it has four subunits, a heamoblobin molecule can combine reversibly with up to
four oxygen molecules forming oxyheamoglobin molecules.
Hb + 4O HbO8
beta1
beta2
Haem
group
globin
Red Blood
Cell
alpha2
alpha1

4. Transport of O2 by the Heamoglobin
When an heamoglobin molecule is not bonded to oxygen molecule, deoxyheamoglobin (heamoglobin without O2 molecules) stays in tensed state.
When the first molecule of oxygen combines with a heamoglobin, oxyheamoglobin shifts to relaxed state in which the shape of heamoglobin changes hence it becomes easier for other three oxygen molecules to bind to the other haems.

5. Transport of O2 by the Heamoglobin
Partial Pressure of Oxygen, pO2
Partial Pressure is the pressure exerted by the one gas in a mixture.
The partial pressure of oxygen (pO2) is a measure of oxygen concentration. The amount of oxygen that combines depends upon this partial pressure. Heamoglobin does not necessarily unload all of its oxygen as it passes through the body tissues.
Heamoglobin requires some conditions in order to load or unload its oxygens.
Conditions for heamoglobin to load oxygen
Conditions for heamoglobin to unload oxygen 1
High pO2
Low pO2 2
Low pCO2
High pCO2 3
Alkalinity
Inncreased acidity 4
Lower temperature
Higher temperature

6. Transport of O2 by the Heamoglobin
Because of the conditions mentioned before, red blood cells hence heamoglobins are very efficient in transporting oxygen from alveoli in the lungs to the respiring cells in the tissues.
Alveoli
The tissue fluid surrounds the cells and supplies them with oxygen. As the cells respire, they produce carbondioxide so the tissue fluid needs to be replaced continually with the fresh one. In order to supply cells with oxygen, the red blood cells move to the lungs where there is high pO2 and increased alkalinity. They combine with the oxygen molecules and move to the respiring cells where there is high pCO2 and acidity. As a result, they give up their oxygens and oxygen molecules reach respiring cells via tissue fluid.
Red blood cell
Respiring cells
Tissue fluid

7. Transport of O2 by theHeamoglobin
100% saturation means that every
Heamoglobin molecule carries max
Of molecules of oxygen
The releationship between the partial pressure of oxygen and quantity of the oxygen combined with haemoglobin is shown by S-shaped DISSOCIATION CURVES.
Dissociation curve for an adult
Haemoglobin (Hb).
0% saturation means that none of the
Heamoglobin molecules carry any oxygen

8. Transport of O2 by theHeamoglobin
Dissociation Curve
WHY S-SHAPED?
As mentioned before, when heamoglobin combines with first oxygen molecule, it alters its shape to anable other molecules to join on it easily. However as heamoglobin starts to become fully saturated, it becomes harder for more oxygen molecules to join.
Steep bit in the middle means that it is very easy for oxygen molecules to join while shallow bits at the ends show that it is harder for oxygen molecules to join.
◊Steep bits in the middle means that it is for oxygen molecules to join the heamoglobin molecules.
◊The shallow parts at each end show that it is harder now for oxygen molecules to be loaded.

9. Transport of Carbondioxide in the Blood
A)As sodium hydrogencarbonate in plasma
Carbondioxide, which is produced in respiration, diffuses from body tissues into the blood where most of it, is taken by the red blood cells.
In red blood cells,carbondioxide combines with water to form carbonic acid, H2CO3. This reaction is catalysed an enyzme called carbonic anhydrase.
Then carbonic acid dissociates into hydrogencarbonate and hydrogen ions.
Hydrogen ions causes oxyhaemoglobin to dissociate. Therefore oxygen diffuses into the cells for respiration.

10. Transport of Carbondioxide in the Blood
The hydrogen ions combine with haemoglobin and form haemoglobinic acid. This meas that haemoglobin molecules act as buffers mopping up hydrogen ions and preventing changes in pH.
Hydrogencarbonate ions are pumped out of the red blood cells and enter the
plasma where they combine with sodium so becoming sodium hydrogencarbonate.
Ξ To make sure that red blood cells remain electrically neutral, chloride ions
move into the red blood cells by a process known as Chloride Shift!

11. Transport of Carbondioxide in the Blood
B)As carbomino compounds in red cells
Carbon dioxide also reacts with heamoglobin and other proteins to form compounds known as CARBOMINO COPMPOUNDS.
C) In simple solution, dissolved in the plasma
Carbon dioxide is relatively soluble in in the plasma and a small percentage of it is transported in the form of a simple solution, dissolved in the plasma.

12. Ф BOHR EFFECT Ф
The exact shape of the dissociation curve depends on a number of factors such as
Partial pressure of carbondioxide (pCO2)
Temperature pH
Because of the Bohr Effect, an increase in partial pessure of carbon dioxide, a decrease in pH or increased temperature causes hemoglobin to bind to oxygen with less affinity.
Bohr Effect is very important in respiring tissues since pCO2 increases in tissue fluid. This causes oxyhaemoglobin to release its oxygens readily causing more oxygen to be delivered to the tissues needed for respiration.

13. Ф BOHR EFFECT Ф As shown on the dissociation
curve, when carbon dioxide
level increases, the dissociation curve shifts to right. This prooves that more oxygen is released from the blood.
The lower the saturation of O2 in the blood, the more O2 will be released.

14. Different Species Have Different Dissociation Curves
Hawk; an active animal with a high
Respiratory rate where there is
Plenty of oxygen.
% saturation
of haemoglobin with oxygen
Human
Llama living in Andes; an animal
Living at high attitudes where the
Partial pressure of oxygen is lower
Lugworm, animal living in depleted
Oxygen environment.
Oxygen tension / kPa

15. Different Species Have Different Dissociation Curves
As shown on the dissociation curve, the chemical composition of heamoglobin and its oxygen carrying capacity is different in different species.
Organisms living in depleted O2 environment have dissociation
curves to the left of human ones. Eg lugworms and Llamas.
Organisms that are active and have higher partial pressure of oxygen in their environments have curves shifting to right of the human ones. Eg hawks
That means heamoglobins of lugworms have more affinity for oxygen than that of the others’.
Lugworm
Llama
Human
% saturation
of haemoglobin with oxygen
Hawk
Oxygen tension / kPa

16. Ж SUMMARY Ж
Main Points
≈ Oxygen molecules are transported in the blood by the heamoglobins in the red blood cells
≈ Carbondioxide molecules are carried by 3 ways; as simple solutions dissolved in plasma, as carbomino compounds and as sodium hydrogencarbonate
≈ The amount of oxygen that binds to heamoglobin molecules depends on partial pressure of oxygen. It is a measure of oxygen concentration.
≈ The dissociation curve shows the releationship between the partial pressure of oxygen and the quantity of oxygen molecules combining with the heamoglobin.
≈ BOHR EFFECT is an effect by which increase in partial pressure of carbondioxide, decrease in pH and high temperature causes a reduction of the affinity of heamoglobin for oxygen.
≈ On the dissocaition curves, the curves shifting to left of the others means increased affinity of oxygen for that heamoglobin.

17. THE END
Thank You For Listening
Created by Ovgu Ozenli