Simplify the following text for a Grade 7 native English-speaking person.
Original: 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 .
Simplified: The cecum is a pouch-like structure of the colon . The appendix is near the junction of the small intestine and the large intestine .