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Minggu, 24 Maret 2013

The Large Intestines


THE LARGE INTESTINES

GENERAL FUNCTION
     The primary function of the large intestines is the salvaging of water and
electrolytes (salts). Most of the end products of digestion have already been absorbed in the small intestines. Within the large intestines, the contents are first a watery fluid. Thus, the large intestines are important in the conservation of water for use by the body. The large intestines remove water until a nearly solid mass is formed before defecation, the evacuation of feces.

MAJOR SUBDIVISIONS
   The major subdivisions of the large intestines are the cecum (with vermiform or
"worm-shaped" appendix), the ascending colon, the transverse colon, the descending colon, and the sigmoid colon. The fecal mass is stored in the sigmoid colon until passed into the rectum.

RECTUM, ANAL CANAL, AND ANUS
   Rectum means "straight." However, this six-inch tubular structure would actually look a bit wave-like from the front. From the side, one would see that it was curved to conform the sacrum (at the lower end of the spinal column). The final storage of feces is in the rectum. The rectum terminates in the narrow anal canal, which is about one and one-half inches long in the adult. At the end of the anal canal is the opening called the anus. Muscles called the anal sphincters aid in the retention of feces until defecation.



Large Intestine
The large intestine forms an upside down U over the coiled small intestine. It begins at the lower right-hand side of the body and ends on the lower left-hand side.  The large intestine is about 5-6 feet long. 

It has 3 parts:
  1.  the cecum
  2. the colon
  3. and the rectum.                                                                            

 The  cecum is a pouch at the beginning of the large intestine. This area allows food to pass from the small intestine to the large intestine. The colon is where fluids and salts are absorbed and extends from the cecum to the rectum. The last part of the large intestine is the rectum, which is where feces (waste material)is stored before leaving the body through the anus. The main job of the large intestine is to remove water and salts (electrolytes) from the undigested material and to form solid waste that can be excreted.  Bacteria in the large intestine help to break down the undigested materials. The remaining contents of the large intestine are moved toward the rectum, where feces are stored until they leave the body through the anus as a bowel movement.






Large Intestine







Beneath the epithelium, but still within the tunica mucosa is a layer - the lamina propria - of loose connective tissue through which course blood vessels and lymphatics that supply the epithelium. This layer also contains lymphatic nodules important to immune functions of the digestive tract. Finally, beneath the lamina propropria is a thin layer of smooth muscle (lamina muscularis mucosae) which permits the mucosa to dynamically move and fold.




Sumber : Bpk. Dr. Iskandar Zulkarnain

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