Wednesday, February 29, 2012

Large Intestine

Large Intestine: the large intestine is joined at the bottom of the small intestine. Follow the coils of the small intestine. The end of the ileum enters the large intestine. At this juncture the cecum, a short blind sac about 2 cm. long, is formed. This organ takes about sixteen hours to finish the process of the digestive system. Food is no longer broken down at this stage of the GI tract. The colon absorbs vitamins such as K, B12, thiamine and riboflavin. The large intestine also compacts feces and stores fecal matter in the rectum until it can be released by the anus in defecation.
      · Cecum: the cecum connects the ileum with the ascending colon of the large intestine.
      · Ileocecal Valve: the ileocecal valve is situated at the junction of the small intestine (ileum) and the large     intestine. This passage limits the reflux of the colonic contents into the ileum.
      · Ascending Colon: the ascending colon is the first section of the large intestine. The main function of this section is to remove the water and other nutrients from waste material and recycle it back into the body by the blood stream. The waste material is then moved upwards towards the transverse section of the colon by peristalus (muscle contraction).
      · Transverse Colon: the transverse colon is the second section of the large intestine and connects the ascending colon to the descending colon. The transverse colon expulses the left over water and nutrients that came from the ascending colon into the blood stream and uses peristalus (muscle contraction) and carries the waste to the descending colon.
      · Descending Colon: the descending colon is the third section of the large intestine and is connected to the transverse colon and the sigmoid colon. The descending colon expulses of any left over water and nutrients into the blood stream and is moved to the sigmoid colon by peristalus (muscle contraction).
      · Sigmoid Colon: the sigmoid colon is the fourth section of the large intestine that is connected in between the descending colon and the rectum. The sigmoid colon also absorbs water and nutrients into the blood stream for recycling.
      · Rectum: the rectum is the fifth and final section of the large intestine that is connected between the sigmoid colon and the anus. It is the posterior dorsal portion of the large intestine and descends along the midline through the pelvic girdle to the onus, the intestinal opening to the exterior. The rectum, just like the rest of the large intestine, is a temporary storage place for fecal matter. When it becomes full the pressure from the fecal matter forces the anal canal apart making the fecal matter enter the canal and uses peristalic waves (muscle contraction) to propel the fecal matter out of the rectum forcing the anal muscles up.  
  · Anus: the anus is the intestinal opening to the exterior of the body. It is found underneath the pig's tail and expels the feces (waste) out of the body using peristalus (muscle contraction).
The spiral colon is a compact coiled mass clearly visible upon the left ventral surface. It is shorter, darker, and thicker than the small intestine. It is the major portion of the large intestine.





Anus

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