Write a note on respiratory pigments.

Explanation

Haemoglobin belongs to the class of conjugated protein. The iron containing pigment portion haem constitutes only 4% and the rest colourless protein. Molecular weight is 68,000 and contains 4 atoms of iron.
Methaemoglobin : If the iron component of the haem moietries is in the ferric state, than the normal ferrous state is called methacmoglobin. It does not bind `O_2`. RBC contains less than 1% methaemoglobin.