Inflammatory Bowel Disease

Inflammatory bowel disease or IBD for short is a chronic condition that causes inflammation and ulceration in the intestinal tract.

The two major types of IBD are Crohn's disease or CD and ulcerative colitis or UC. Ok.

So, the gastrointestinal tract is a hollow tube that includes the oral cavity, pharynx, esophagus, stomach, small and large intestines and anus.

Now zooming in on a cross section of the intestines, we can see that the walls are typically made up of the same four layers of tissue from the inside out.

There's the mucosa, the inner lining that consists of mucosal, epithelium, connective tissue and smooth muscle that secretes mucus and digestive enzymes.

It also serves as a highly selective barrier that absorbs nutrients and water while preventing absorption of harmful substances and bacteria moving outward.

The submucosa is a dense layer of tissue that provides support and contains blood vessels, lymphatics and nerves. Next is the muscularis which consists of a network of nerve fibers and layers of smooth muscle that contract to move intestinal contents forward in a process called peristalsis.

And finally, the outermost layer is the cirrhosa composed of connective tissue. It anchors the intestines in place and secretes a lubricating fluid that promotes smooth movement of the intestines within the abdominal cavity.

Now, the exact cause of IBD is unknown. However, it's likely that a combination of genetic environmental and immune factors alters the protective barrier function of the mucosal epithelium leading to a dysregulated immune response.

On top of that, the normal gut microbiome may also be altered resulting in an increasing population of potentially pathogenic bacteria.

Risk factors include having a family history of IBD, dietary patterns such as a diet high in processed foods and having another autoimmune disease.

Interestingly, nicotine use increases the risk and disease severity of CD. While it's associated with later onset and less disease severity of UC IBD occurs due to autoimmune activity, which is when the immune system attacks its own tissues, causing inflammation and tissue damage.

In UC inflammation affects the large intestine often starting in the rectum and spreading from there in a continuous fashion, damaging the mucosa and submucosa, the mucosa becomes fragile and small hemorrhages occur.

And as the disease progresses, these hemorrhagic areas coalesce into ulcers. On the other hand, CD is not limited to just the large intestine rather, it can occur anywhere from the mouth to the anus.

Though it often spares the rectum. The characteristic lesions in CD are masses of inflammatory tissue surrounded by ulcerations that take on a cobblestone appearance.

Also, unlike the continuous lesions seen in UC lesions in CD are discontinuous, meaning there are large areas of healthy tissue, between damaged areas, which are called skip lesions.

Also, unlike you see, the inflammation in CD penetrates deeply through all layers of the intestinal wall, called transmural inflammation.

As the disease progresses, fistulas and strictures can occur. Fistulas are abnormal connections that form between the intestinal wall and a neighboring structure like between loops of the small intestine or between the large intestine and the bladder or rectum, which can increase the risk of intraabdominal infection.

Strictures are where areas of the intestinal lumen become narrow which can cause a partial or complete obstruction. Clinical manifestations of IBD generally include changes in bowel patterns like crampy, abdominal pain, diarrhea, unintentional weight loss and fatigue.

UC commonly presents with diarrhea that's often bloody as well as fecal urgency. In contrast, the diarrhea in CD is usually not bloody.

Finally, all types of IBD have an increased risk of gastrointestinal cancer. All right.

As a quick recap inflammatory bowel disease is a chronic inflammatory condition and includes Crohn's disease or CD and ulcerative colitis or UC.

The inflammation in UC affects the mucosa and submucosa of the large intestine and creates continuous areas of ulceration.

In CD, inflammation can occur anywhere from the mouth to the anus though it often spares the rectum, deep transmural inflammation, skip lesions and cobblestone lesions are also characteristic of CD as well as strictures and fistulas.

Clinical manifestations of IBD include crampy, abdominal pain, unintentional weight loss, fatigue and diarrhea, which in you see is often bloody.