The Gastrointestinal System In The Human Body

The Gastrointestinal System The gastrointestinal tract is a collection of organs that work together to enable the body to digest and absorb numerous substances. It is often described as a long muscular tube starting at the mouth, and ending at the anus. The esophagus, stomach, small intestine (consisting of the duodenum, jejunum, and the ileum), and the large intestine (consisting of the cecum, ascending, transverse, and descending colon, the sigmoid, rectum, and anus), all make up the gastrointestinal tract. The esophagus is the starting point for the gastrointestinal tract, it is a muscular tube that measures approximately twenty-five centimeters from the pharynx to the stomach. It passes through the diaphragm, and has two curvatures which …show more content…
The duodenum then connects to the jejunum at the duodenoljejunal junction, and the jejunum begins at the ligament of Treitz. The jejunum occupies about two fifths of the small intestine and has a wider and thicker wall than the ileum. The ileum is the longest section of the small intestine, measuring approximately thirteen feet. It extends from the jejunum to the ileo-cecal valve where the small intestine joins the large intestine. The large intestine (colon) is about five feet, and measures four to nine millimeters thick un-distended. The cecum is the first part of the large intestine and has the appendix attached to its inferior portion. The appendix is located in the right lower quadrant of the abdomen and measure eight to ten centimeters in length, six millimeters in diameter, and two millimeters in wall thickness. From the cecum, the colon courses superior which is known as the ascending colon, which in turn, becomes the transverse colon, and finally the colon returns inferior as the descending colon and slightly courses medial as the sigmoid colon. The rectum leads into the anus. The anus then exits to the outside of the body, thus …show more content…
During the fourth week of a pregnancy, the gut tube is formed from the endoderm that lines the yolk sac. The gut tube is divided into three regions: the foregut, the midgut, and the hindgut. The foregut differentiates into the trachea, pharynx, lungs, esophagus, stomach, liver, pancreas, upper duodenum, and the gallbladder. These structures get their blood supply from the celiac artery. The midgut derivatives include the lower duodenum, jejunum, ileum, cecum, ascending colon, transverse colon, and the appendix; these structures get their blood supply from the superior mesenteric artery. Finally, the hindgut becomes the descending colon, the sigmoid colon, rectum, and the anus, and they receive blood from the inferior mesenteric artery. By the sixth week, the dorsal mesentery of the stomach becomes the greater omentum, and the lesser omentum is formed by the mesentery between the liver and the stomach; thus completing the formation of the gastrointestinal tract in