The appendix serves no purpose. However, according to one theory, the appendix works as a reservoir for beneficial bacteria, “rebooting” the digestive system following diarrheal disorders. Another theory is that according to some specialists, the appendix is a remnant of our evolutionary past.

The primary function of the gallbladder is to store bile. Bile aids in the breakdown of fats by the digestive system. Bile is a viscous fluid composed primarily of cholesterol, bilirubin, and bile salts.

The ileum aids in the further digestion of food that has passed through the stomach and other sections of the small intestine. It takes nutrients (vitamins, minerals, carbs, lipids, and proteins) and water from food and converts them into energy for the body.

Reference:

Cleveland Clinic. (n.d.). Gallbladder: What Is It, Function, Location & Anatomy. Retrieved from https://my.clevelandclinic.org/health/body/21690-gallbladder#:~:text=Your%20gallbladder%20is%20part%20of,cholesterol%2C%20bilirubin%20and%20bile%20salts.

NIH (n.d.). NCI Dictionary of Cancer Terms. National Cancer Institute. Retrieved from https://www.cancer.gov/publications/dictionaries/cancer-terms/def/ileum

WebMD (2019, May 18). The Appendix (Human Anatomy): Appendix Picture, Definition, Function, Conditions, Tests, and Treatments. Retrieved from https://www.webmd.com/digestive-disorders/picture-of-the-appendix#:~:text=Normally%2C%20the%20appendix%20sits%20in,remnant%20from%20our%20evolutionary%20past.