The first part of small intestine is called duodenum. small intestine is divided into three parts: deudenum, jejunum, ileum. www.cancer.gov. Stomach has constrictions (sphincters) on both of its ends. read more
Full Answer. The duodenum, or first part of the small intestine, receives digestive system contents from the stomach through a tight band of muscle known as the pyloric sphincter. read more