Sorry William for my tech jargon
I'm a student nurse and deal with these issues of metabolism and homeostasis every day.
Peristalsis is movement of food down the GI tract. Muscles of the stomach and intestines help to mix and absorb nutrients via rhythmic muscle contraction and relaxation. When person is sedated for surgery with general anesthesia, all body's natural processes slow down...peristalsis stops as well. After surgery the body slowly regain normal functions. If the person didn't eat all day prior surgery (because of the risks for aspiration--chocking during operation) and Dr. orders bed rest post-op...yes, the patient will have difficulty absorbing foods and might get constipated. Why do you think Drs wants you to begin walking hallways same day or the next even if patients are in pain?!
I hope it clarifies a little....or confuse you even more...
