Form Of Chronic Inflammatory Bowel Disease Biology Essay

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Ulcerative Colitis is a form of chronic inflammatory bowel disease that effects the colon mostly in the recto-sigmoid region. It is a form of colitis, in which the colon becomes inflamed and develops tiny open sores in the lining of colon (Crohn's & Colitis foundation of America, 2013).

This tiny open sores or ulcers, produce pus and mucus. Ulcerative colitis comes in phases with gradual disintegration of the intestinal wall with abdominal pain and cramps, rectal bleeding and diarrhea containing blood, pus and mucus. But in some cases, toxic megacolon (extreme dilatation of a segment of colon) and potential perforation in the peritoneal cavity might occur due to a very severe acute process ( Bontrager & Lampignano, 2010).

Ulcerative Colitis can affect people at any age but it often occurs in teenagers and young adults between the age of 15-30 years. Crohn's & Colitis foundation of America state that, Ulcerative Colitis is the result of an abnormal body response to our body's immune system. The immune system that consists of a collection of cells and protein protects our body from potentially harmful infectious microorganisms. However the immune system attacks our food, bacteria and other materials mistaking it for harmful pathogens. When this happens, our body will send white blood cells into the lining of he intestines which will produce chronic inflammation and ulceration.



2.1 Anatomy of Colon

Figure 1: Colon or large intestines was divided into six region

The colon or large intestine is the last part of digestive system. It is 1.5m (5ft) long and 6.5cm (2.5 inch) in diameter which covers the intraperitoneal cavity. It function is to removes water and salt from solid waste before the defecation process takes place. Colon was different from small intestines as it does not take part in the major role of absorption of foods and nutrient. Somehow, it does absorb water, sodium and some fat soluble vitamin. Colon or large intestines consist of six sections:

Cecum Intestinal pouch located at the junction of large and small intestines which is important in cellulose digestion.

Ascending colon Lies vertically in the lateral part of abdominal cavity.

Transverse colon A horizontal course from right to left and just below the spleen it takes right angle turn to form descending colon.

Descending colon Lies vertically in the most lateral left part of abdominal cavity. Consist of sigmoid colon and rectum at the distal portion.

Sigmoid colon The S-shape curve lies between descending colon and rectum. Its length is about 40cm.

Rectum The terminal part of large intestine that ends with anus. About 12cm in length.

2.1.1 Histology of Colon

Figure 2: Four different linings in the wall of colon

The wall of colon contains four different layers which is :

(a)Mucosa layer The mucosa layer consist of epithelium, connective tissue and smooth muscle. The epithelium contains intestinal gland that composed of absorptive and goblet cells. The function of absorptive cell is to absorbs water while goblet cells secretes mucus that act as a lubricant The nodules were found in connective tissue and it will extends until submuscularis mucosa of submucosa.

(b) Submucosa Compose of connective tissue and some amount of fat.

(c) Muscularis Contains two layers of smooth muscle that is internal circular layer and external longitudinal layer. The external longitudinal muscle layer runs most of the length of colon. Muscularis layer enclosed by 3 conspicuous band performing teniae coli.

(d) Serosa Part of visceral peritoneum that contains fat and connected to teniae coli.

2.2 Etiology

The etiology of this cause is unknown (Kowalczyk & D. Mace, 2009, p. 119). But it is thought that genes, environment and immune system might be the risk factors of having Ulcerative Colitis.

2.2.1 Genetic Factor

Researchers have found that Ulcerative Colitis tends to run in families. The risk of having inflammatory bowel disease is between 5.2 percent and 22.5 percent for first degree relatives (Crohns & Colitis foundation of America, 2013). About 1 in 5 people that having Ulcerative Colitis had close relatives infected with the same disease (Christian Nordqvist, 2009). Moreover, according to D. Basson (2009), a family history observed in 1 in 6 relatives associate with Ulcerative Colitis will developed higher risk. In addition, levels of Ulcerative Colitis are higher in certain ethnic groups and identical twins. This shows that Ulcerative colitis somehow can be genetically inherited.

2.2.2 Environment Factor

How people live seems to play a role in the development of this disease. Air pollution, cigarette smoking, hygiene and diet can be the contribution factor to Ulcerative Colitis. Diet affected a person to a higher risk especially those typical European. These people diet is high in carbohydrate and fats, which may explain why Asian people who tend to eat a diet low in carbohydrate and fats are less likely affected by this disease. Besides, high consumption of unsaturated fat and vitamin B6 might also increase the risk of getting the disease (Geerling et al., 2000).

2.2.3 Immune System

Some researchers think virus can trigger Ulcerative Colitis (Mayo Clinic Staff, 2012). The immune system protects our body from infections. But in Ulcerative Colitis, for some unknown reason, after the infection has gone the immune system continues to respond which will later causing inflammation. This condition is known as autoimmune response.

2.3 Histopathology

Ulcerative Colitis basically starts from rectum and spreads proximally to sigmoid and later involves a variable length of colon. Inflammation and ulcers mostly affected only the innermost lining of colon wall. The greater the affected area, the greater the symptoms will be.

The plain appearance varies with the activity of the disease. Only the mucosa will be seen with variable ulcers (Fig. 3). While, the appearance of fistula, stenosis and significant thickening othe wall will not be seen rarely (K. Geboes, n.d. ).

Figure 3: (A) A normal vacularised mucosa of colon (B) An inflammation on the mucosa wall

Ulcers of mucosa

An abcess will be visualized in the crypt cells after the inflammation takes place at the mucosa and submucosa (reticulum fibers beneath the mucosal epithelium) (Fig 4). This will cause the cell to loss their blood supply and leading to epithelial necrosis and mucosal ulceration (Kowalczyk & D. Mace, 2009). The mucosa then will be replaced by fibrous tissue which will appear as “cobblestones”. Inaddition, Johns Hopkins Medicine (n.d.) state that, the severity of the disease might be variable histologically, ranging from minimal to florid ulceration and dysplasia. Carcinoma might occur. The lesion of Ulcerative Colitis was the crypt abcess, in which the epithelium of the crypt cells breaks down and the lumen fills with polymorphonuclear cells. The lamina propria is infiltrate with leukocytes. This will cause the normal build of crypt cell to damage and causes the scarring shortens with narrowed colon (Johns Hopkins Med., n.d.).

Figure 4: Microscopic view of the mucosa, showing diffuse active inflammation with crypt abscess and glandular architectural distortion

Following the healing of mucosal ulcers, the pseudopolyps will appear typically small and multiple and can be found in sigmoid and descending colon but rarely found in rectum (Fig. 5).

Figure 5: Ulcerated hemorrhagic surface with knobby pseudopolyps

2.3 Pathophysiology