Final answer:
The small intestine's divisions in sequential order as food passes through them are the duodenum, jejunum, and ileum.
Step-by-step explanation:
The proper order of the divisions of the small intestine as food passes through the gastrointestinal tract is the duodenum, followed by the jejunum, and finally the ileum. The duodenum is the first section and the shortest, where most chemical digestion occurs. The jejunum follows as the second part, playing a critical role in the absorption of nutrients into the blood. Lastly, the ileum continues the process of absorption and facilitates the transition of the remaining chyme toward the large intestine.