The rectum is made up of little storage spaces called transverse folds. Transverse folds are fold-like structures that keep stool in place until a bowel movements. When stool is ready to be excreted, it enters the lower rectum, moves into the anal canal, and then passes through the anus. The rectum is approximately 5 inches long and 1.5 inches wide.
The Rectum is the number five in the diagram below
Since the rectum is the next to last organ prior to the removal of stools through defecation, in case problems occur within the rectum that cause bleeding, likely the blood will not have had much time to sit and decay and will have preserved its original crimson red color. Typically, bright red blood in stools occurs if the blood mixes in with the stools towards the end of the digestion cycle. It the blood mixes in with the stools earlier during the digestion process, likely the blood will have time to turn black by the time is exists the body.