The cecum is a pouch-like structure of the colon and the appendix is near the junction of the small intestine and the large intestine and has abundant infection-fighting lymphoid cells, which suggests it plays a role in the immune system.nother theory as to the reason for an appendix is it refers to the time when man was exclusively a herbivore. Dr. Jerome Sullivan. 'noticed' during his studies of iron overload that the loss of the appendix COMMONLY was found in those with iron excess.