Title: Small intestine | anatomy | Britannica
Headings: 
Small intestine
anatomy
Consider whether the continuous band of membranous tissue around humans' intestines should be deemed an organ
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Content: The mesentery contains areas of fat that help retain heat in the organs, as well as an extensive web of blood vessels. Nerves lead to the small intestine from two divisions of the autonomic nervous system: parasympathetic nerves initiate muscular contractions that move food along the tract ( peristalsis ), and sympathetic nerves suppress intestinal movements. small intestine
The small intestine contains many distinct types of cells, each of which serves a specific function. Encyclopædia Britannica, Inc.
Britannica Quiz
The Human Body
You may know that the human brain is composed of two halves, but what fraction of the human body is made up of blood? Test both halves of your mind in this human anatomy quiz. Three successive regions of the small intestine are customarily distinguished: duodenum, jejunum, and ileum. These regions form one continuous tube, and, although each area exhibits certain characteristic differences, there are no distinctly marked separations between them. The first area, the duodenum, is adjacent to the stomach;