Define collagen fibres and elastin fibres.
Collagen fibres, chiefly made up of collagen proteins, can resist considerable tensile forces
without significant increase in their length. At the same time they
are pliable and can bend easily. On the other hand, elastin fibres,
composed mainly of elastin proteins, are highly retractile and can be
stretched (like a rubber band) and they return to their original length
when tension is released.