1. increased pH
Transport of Oxygen
Haemoglobin is a red coloured iron containing pigment present in the
RBCs. O2 can bind with haemoglobin in a reversible manner to form
oxyhaemoglobin. Each haemoglobin molecule can carry a maximum of
four molecules of O2. Binding of oxygen with haemoglobin is primarily
related to partial pressure of O2. Partial pressure of CO2, hydrogen ion
concentration and temperature are the other factors which can interfere
with this binding. A sigmoid curve is obtained when percentage saturation
of haemoglobin with O2 is plotted against the
pO2. This curve is called the Oxygen
dissociation curve (Figure 17.5)
and is highly
useful in studying the effect of factors like
pCO2, H+ concentration, etc., on binding of O2
with haemoglobin. In the alveoli, where there
is high pO2, low pCO2, lesser H+ concentration
and lower temperature, the factors are
all favourable for the formation of
oxyhaemoglobin, whereas in the tissues,
where low pO2, high pCO2, high H+
concentration and higher temperature exist,
the conditions are favourable for dissociation
of oxygen from the oxyhaemoglobin. This
clearly indicates that O2 gets bound to
haemoglobin in the lung surface and gets
dissociated at the tissues. Every 100 ml of
oxygenated blood can deliver around 5 ml of
O2 to the tissues under normal physiological
conditions.
