Large Intestine
Large Intestine
By
Pamela Hankinson
For
HAP II
October
Large Intestine Many people often confuse the large intestine with the small intestine. However the large intestine is wider (about 3 inches) yet shorter than the small intestine (in humans about 4.9 feet in length as compared with 22 - 25 feet for the small intestine) and has a smooth inner wall. (Britannica) The large intestine consists of the cecum, ascending, transverse, descending and sigmoid colon, rectum and anus. The longitudinal muscle of the muscularis externa is concentrated into 3 bands called teniae coli. These 3 bands of muscle form pouches (haustra) because they are shorter than the rest of the colon. The epithelium of the mucosa is mostly goblet cells, and has a numerous amount of crypts, there are no villi. (Martini, Ph.D.) The ileocecal valve (sphincter) prevents materials from moving back into the ileum. In the upper half of the large intestine, enzymes from the small intestine complete the digestive process and bacteria produces the B vitamins (B12, thiamin, and riboflavin) as well as vitamin K. (Martini, PhD) The large intestine's primary function is to absorb water and electrolytes from digestive residues and storage of fecal matter until it can be expelled. The large intestine is the last attraction in digestive tube and the location of the terminal phases of digestion. In comparison to other regions of the tube, there are huge differences among species in the relative size and complexity of the large intestine. Nonetheless, in all species it functions in three processes: (Marieb)
*Recovery of water and electrolytes *Formation and storage of feces
*Microbial fermentation A wide variety of diseases and disorders occur in the large intestine. The most frequent and common disease of the large intestine is Crohn's disease. The cause of Crohn's disease is unknown. ( Britannica) Apart from the greater tendency for fistulas to form and for the wall
By
Pamela Hankinson
For
HAP II
October
Large Intestine Many people often confuse the large intestine with the small intestine. However the large intestine is wider (about 3 inches) yet shorter than the small intestine (in humans about 4.9 feet in length as compared with 22 - 25 feet for the small intestine) and has a smooth inner wall. (Britannica) The large intestine consists of the cecum, ascending, transverse, descending and sigmoid colon, rectum and anus. The longitudinal muscle of the muscularis externa is concentrated into 3 bands called teniae coli. These 3 bands of muscle form pouches (haustra) because they are shorter than the rest of the colon. The epithelium of the mucosa is mostly goblet cells, and has a numerous amount of crypts, there are no villi. (Martini, Ph.D.) The ileocecal valve (sphincter) prevents materials from moving back into the ileum. In the upper half of the large intestine, enzymes from the small intestine complete the digestive process and bacteria produces the B vitamins (B12, thiamin, and riboflavin) as well as vitamin K. (Martini, PhD) The large intestine's primary function is to absorb water and electrolytes from digestive residues and storage of fecal matter until it can be expelled. The large intestine is the last attraction in digestive tube and the location of the terminal phases of digestion. In comparison to other regions of the tube, there are huge differences among species in the relative size and complexity of the large intestine. Nonetheless, in all species it functions in three processes: (Marieb)
*Recovery of water and electrolytes *Formation and storage of feces
*Microbial fermentation A wide variety of diseases and disorders occur in the large intestine. The most frequent and common disease of the large intestine is Crohn's disease. The cause of Crohn's disease is unknown. ( Britannica) Apart from the greater tendency for fistulas to form and for the wall
Bibliography: Marieb, E.N., & Mitchell, S.J. (2008) Human Anatomy & physiology Laboratory Manual (8th Ed.). San Francisco: Pearson Education, Inc. Martini, Ph.D. F.H. (2006). Fundamentals of Anatomy & physiology (7th Ed.). San Francisco: Pearson Education, Inc. Large intestine. (2007). In Encyclopedia Britannica. Retrieved October 5, 2007, from Encyclopedia Britannica Online: http://www.britannica.com/eb/article-9047200 Lactose intolerance. (2007). National Digestive Diseases Information Clearinghouse. Retrieved October 5, 2007, from NDDIC online http://digestive.niddk.nih.gov/ddiseases/pubs/lactoseintolerance/