bowel vs small intestine

bowel

noun
  • The entrails or intestines; the internal organs of the stomach. 

  • A part or division of the intestines, usually the large intestine. 

  • The (deep) interior of something. 

small intestine

noun
  • The upper part of the intestine, between the stomach and the large intestine, divided into the duodenum, the jejunum and the ileum. 

How often have the words bowel and small intestine occurred in a corpus of books? (source: Google Ngram Viewer )