1. Introduction
• Blood itself not carrier of the respiratory gases but
contains a respiratory pigment which actually act as
the carrier of the respiratory gases because this
pigment has a special affinity for respiratory gases.
• The respiratory pigment in its nature varies in different
animals.
• Respiratory pigment differ in their chemical
constitution in different group of animals and even in
the same phyla there may be several types of pigment.
• These pigment includes the cytochrome the
flavoprotein and other colored molecules of protein
called “chromoprotein” which are significance in the
transport of respiratory gases and impart or definite
color to the body fluid.
2. Defination
• A respiratory pigment is a molecule such as
haemoglobin in invertebrates and other vertebrates ,
that increases the oxygen carrying capacity of the
blood.
or
• “Respiratory pigment are coloured substance present
in blood transporting the oxygen and carbon dioxide.”
or
• “Respiratory pigment are circulatory pigment which
mediate transfer of respiratory gases at the
extracellular and intracellular level.”
3. Characteristics of respiratory pigment
• They are colored pigment .
• They have special affinities for respiratory
gases .
• They are distributed either in the blood or in
the body fluid.
• They are colored proteins which contain a
metallic ion.
• The combines with oxygen and carbon dioxide
and play key role in the transportation.
4. Type of respiratory pigment –
1.Haemoglobin
2.Haemocyanin
3.Chlorocruorin
4.Haemerythrin
5.Pinnaglobin
6.Echinochrome
7.Molpadin
8.Vanadiun
9. Neuroglobins
10. Cytoglobins
5. General account of respiratory
pigment
HAEMOGLOBIN :-
• Haemoglobin occurs in the blood plasma of
invertebrates . It is also called erythrocrurin .
• It is a chromoprotein (conjugated protein).
• It is found in few holothurians , several
crustaceans , chironomous insect , planorbis ,
annelids , parasitic nematodes , flatworm etc.
• Molecular weight - 68000 kDa .
• It is red in color metallic group present is IRON.
6. CHEMICAL STRUCTURE :-
• Haemoglobin is composed of two component namely a
protein component called Globin & a non- protein
component called Haem.
• Globin formed of four polypeptide chains of the four two
are identical and called α (alfa )chain each α chain formed
of 141 amino acids . The other two identical chains are
called β chain which contain 146 amino acids .
• The heam is formed of iron and porphyrin . The iron is
present in the ferrous from.
• The porphyrin is the pigment and it gives red colour to the
haemoglobin .
• There are four haem molecules in one haemoglobin .
7.
8. • When haemoglobin is treated with HCl , it is
froms a brown colored pigment called “ acid
haematin”
• When haemoglobin is treated with Glacial
acitic acid it froms “ haemin crystal ” .
