Ah, the innocence of medical school. This is a story from my third year of clinical clerkship, when I started rotating through the hospital wards, starting with internal medicine. I was matched to the gastrointestinal team, so I can recite the bacterial causes of bloody diarrhea to this day.
One patient taught me about ulcerative colitis...and a few other things.
You can also find this essay in my book, The Most Unfeeling Doctor in the World and Other True Tales from the Emergency Room.