Large intestine

Apr 14, 2012 , Danica Deretić

tluste-strevo.jpg - kopie
tluste-strevo.jpg - kopie
The large intestine is the final part of the digestive tract. It connects to the small intestine and ends with the rectum. The large intestine mainly serves to reclaim water and by doing this to condense any remaining digested matter and turn it into stool. The large intestine can be affected by a range of diseases, the most severe of which is a cancer of the large intestine, medically known as a colorectal carcinoma.

Large intestine

Large intestine is a tube organ of the digestive system, which connects to the smaller intestine and ends in the rectum. From the smaller intestine it receives digested matter, chyme, which is briefly stored in the large intestine while water is absorbed from it. The rest of the chyme is then solidified and turned into stool.

Anatomy of the large intestine

The large intestine is approximately 1,5 meters long. Its names come from its diameter, which can be up to 7,5 cm. The large intestine is divided into several parts. The first part is the cecum, to which the bottom end of the smaller intestine is joined. The appendix is also located in this part. Cecum with appendix is located in the lower right part of the abdomen, in the iliac pit. Cecum is connected to the ascending colon, which runs upwards towards the liver, then as the transverse colon it turns and follows under the left costal arch. There it turns down again, becoming the descending colon, which runs into the lower left part of the abdomen. The descending colon is connected to the sigmoid colon, which gets its name from its „s“ shape. The sigmoid colon then connects to the rectum.

Function of the large intestine

The large intestine is grooved on the surface. This is caused by contractions of muscle layers in the intestinal walls, which move in order to stir the contents and move it towards the rectum. This causes the outwardly bulging areas of the intestine. The main purpose of the large intestine is to reclaim water and minerals from chyme. Around 1,5 liters of chyme enters the large intestine, which is then concentrated into 100-200 ml during its passage, preventing the loss of fluids and minerals. Another function of the large intestine is storing any undigested remains, which are removed regularly from the body in the form of stool. A necessary part of the large intestine are the intestinal bacteria. We are referring to the natural intestinal microflora. This prevents the propagation of bacteria harmful for the human body. They also produce vitamin K, which is necessary for blood coagulation.

Diseases of the large intestine

Diseases of the large intestine are always connected to digestion and tend to be unpleasant for the patient. This can be why people tend to come late with their issues involving the large intestine. This can have an unfortunate effect on the treatment. We can encounter inflammatory disease, functional disorders and even cancerous diseases of the large intestine.

Appendicitis

Likely the most well known and common disease is the appendicitis. This is an inflammation of a blind-ended tube, the appendix, attached to the cecum. This is a disease belonging among the acute abdomen disorders and required immediate medical care.

  • The causes of appendicitis are not currently precisely understood. It is assumed that a buildup of stool in the area causes pressure in the appendix and limits its blood supply. Furthermore, bacteria can breed easily in this situation, possibly causing an inflammation.

  • The symptoms are very sudden, the most dominant being a strong pain in the navel area at first, eventually moving to the lower right quadrant of the abdomen. High temperature, nausea and vomiting also tend to be present.

  • Diagnostics of appendicitis are based on manual and ultrasound examination. If the diagnosis still isn't clear afterward, a CT scan is performed.

  • Treatment of appendicitis can be either conservative or surgical. Conservative treatment consists of hospitalization, strict diet and applying cold compresses on the abdomen. Surgical treatment involves the removal of the appendix.

Irritable bowel syndrome

Irritable bowel syndrome is a digestive tract disorder affecting the colon, which is a part of the large intestine. Women tend to be affected up to twice more commonly than men.

  • The causes of irritable bowel syndrome are unknown It was found that the intestinal structure is not damaged in any way, but some psychological conditions of the individual are seen as a triggering factor.

  • The symptoms include diarrhea or constipation excreting mucus, excessive gas and flatulence, intestinal gurgles, unsatisfactory excreting, feeling of bad digestion, stomach pains, tiredness and dizziness.

  • Diagnostics of the irritable bowel syndrome are difficult It is stated that stomach issues lasting for the period of 12 weeks are an indication for the irritable bowel syndrome. The diagnosis is based on laboratory tests, endoscopic and ultrasound examinations. It is very important to perform a gynecological exam in women to rule out a disease of the reproductive organs.

  • The treatment of irritable bowel syndrome involves a change of lifestyle and of diet. More frequent meals with lesser portions are recommended. It’s advisable to increase one's fiber intake and avoid food we already know irritates the bowel. It is also helpful to avoid stress situations.

Crohn's disease

Crohn's disease is an idiopathic inflammatory intestinal disease. Idiopathic means the cause of the disease is not known. Crohn's disease begins in the final part of the small intestine, but spreads to the large intestine and other parts of the digestive tract as well. Because of this the symptoms of Crohn's disease tend to be rather extensive.

  • The symptoms of Crohn's disease can be divided into those afflicting the digestive tract and those outside of this tract. Symptoms afflicting the digestive tract are convulsive stomach pains, diarrhea and somewhat rarely, blood can be present in stool. Sometimes, diarrhea doesn't occur. If the large intestine is affected, frequent diarrhea of smaller volume is typical. Weight loss is also common. High temperature and tiredness tend to appear as well. If the stomach is affected, the symptoms tend to be painful swallowing, stomach pains and vomiting. A result of long lasting inflammation is a thickening of the intestinal walls, causing the narrowing of its lumen and partial or completely blockage of the intestine. This is a life threatening state, which needs to be resolved immediately. Symptoms of Crohn's disease outside of the digestive tract include inflammation of the eyes, especially of the iris and the whites. Further issues are inflammation of joints, finger deformities and loss of bone mass.

  • The diagnostics consist of laboratory tests looking for anemia and signs of inflammation. X-ray contrast examination plays a key role as well. This is an exam where special chemical compounds which absorb great amount of x-rays are used. These compounds show up on the x-ray picture and help spot any changes in the structure or lumen of the intestine. Another possibility is a colonoscopy, an endoscopic method, where a long tube with a camera is inserted in the intestine, allowing the doctor the do a visual exam of the intestine's structure and any changes in it.

  • Treatment of Crohn's disease consists of dietary restrictions, a course of anti-inflammatory drugs and in difficult cases, surgical intervention.

Ulcerous colitis

Ulcerous colitis is an inflammatory disease of the large intestine, afflicting women somewhat more commonly. The cause of this disease is unknown, which is why this disease is counted among the idiopathic intestinal inflammations. It is presumed that autoimmune mechanisms attacking cells of the body itself play a role though.

  • The symptoms of ulcerous colitis are very similar to Crohn's disease. Unlike Crohn's disease, ulcerous colitis only affects the large intestine. The inflammation starts in the rectal area and spreads to nearby part of the intestine. The main symptoms of ulcerous colitis are convulsive stomach pains, frequent watery diarrhea, often mixed with blood.

  • Endoscopic methods are important for diagnosing ulcerous colitis. This mainly refers to colonoscopy.

  • The treatment of ulcerous colitis can be either farmaceutical or surgical. Aminosalicylates and corticosteroids, which are anti-inflammatory drugs, are used. Antibiotics are also employed, as to prevent the spread of bacteria, which would have an adverse effect on the ongoing intestinal inflammation. Immunosupressives are used as well, these being drugs which suppress the organism's immune reaction.

Cancerous diseases of the large intestine

The large intestine is an organ commonly affected by tumors. The tumors can be either benign or malignant. Benign tumors are those that grow slowly, do not spread into their surroundings and do not metastasize, which means they do not form secondary nodes in other organs On the other hand malignant tumors grow rapidly, spread into surrounding areas and by doing this they damage nearby tissues and organs. Malignant tumors metastasize as well.

  • Intestinal polyps are among the benign tumors of the large intestine. There are plainly visible bulges of the intestinal mucous layer, which protrude into the intestine. Polyps generally grow slowly, over the period of several years, but the risk of them turning malignant increases with their size. Intestinal polyps usually manifest by intestinal bleeding. Most commonly, this bleeding is hidden, occult, which cannot be seen in the stool by naked eye. It can only be discovered by specialized tests, which are quite simple, painless, quick and should be undergone by every adult person over 50 years at least once a year. These tests are an important step toward discovering polyps. Sometimes the polyp can manifest by visible bleeding, with the blood being bright red and sticking to the surface of the stool. If there is a suspicion of polyps, a colonoscopy is performed, which allows for immediate removal of the polyps.

  • A colorectal carcinoma is among the malignant tumors. This tumors is one of the most commonly found type of cancer worldwide. Colorectal carcinoma originates from cells lining the inner surface of the intestinal walls. Eating large amount of fat, dark meat, drinking of alcohol, lack of movement and fiber all influence the development of colorectal carcinoma. Only 15% of all carcinomas occur due to genetic predispositions. The symptoms of colorectal carcinoma include changes in stool regularity, shifts between diarrhea and constipation, stool shaped as a long strip, feeling of inadequate voiding of bowel, blood of mucus in stool and loss of weight. Diagnostics consist of careful anamnesis focusing on any occurrence of this carcinoma in family. Laboratory tests, rectal examination end colonoscopy are also performed. The treatment of colorectal carcinoma relies on its size, location and extent of the tumor. Surgical treatment may be used, or chemotherapy. If the tumor is located low, near the rectum, radiotherapy can also be employed.

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