Healthy Intestine
Enterocyte
Enterocytes are cells that line the inside of the intestine. They are responsible for aiding in food digestion by releasing enterokinase. They also play a major role in absorbing nutrients from ingested food.
Small Intestine
The small intestine receives food directly from the stomach. This is where food is further processed, digested, and absorbed. The intestinal villi are finger-like projections that increase the surface area of the gut and increase nutrient absorption.
Colon
The colon is the last stop for digested food. Here is where the stool is formed and a large portion of water is absorbed. This is also where the majority of the bacteria of the microbiome are located.
Diseased Intestine
Celiac Disease
Celiac disease is an inflammatory disease where the immune system recognizes and attacks the gliadin protein found in wheat products. This leads to severe gut problems such as abdominal pain, bloating, diarrhea, and gas.
IBS
IBS (irritable bowel syndrome) is a gut disease that is defined as the presence of abdominal pain/discomfort with altered bowel habits. This can either be an increased amount of diarrhea (IBS-D) or constipation (IBS-C).
Crohn Disease
Chron disease is a chronic inflammatory disease of the gut. The inflammation extends the entire length of the gastrointestinal track, mouth to anus, and includes lesions that entire through the entire thickness of the gut wall.
Ulcerative Colitis
Ulcerative colitis is also a chronic inflammatory disease of the gut. The inflammation is restricted to the colon and involves only the inner lining of the colonic wall. It also begins at the anus and slowly progresses up the color until it reaches the small intestine.
Intestine Treatment
Celiac Disease -> Enterocyte
There are currently no good pharmacological treatments for celiac disease. The best treatment is to avoid eating anything with gluten in it, which is surprisingly most things!
IBS -> Small Intestine
IBS can manifest as either constipation (IBC-C) or diarrhea (IBS-D). One of the treatments for diarrhea is loperamide, which is an u-opioid receptor agonist. Activation of these receptors decreases gut secretions and motility. It has very low bioavailability, so is mostly restricted to the gut.
Crohn/Ulcerative Colitis -> Colon
As Crohn disease and ulcerative colitis are both mediated by the cytokine TNF, antibodies that bind to and neutralize TNF can be used to treat patients. These include the antibodies adalimumab and infliximab.
