2. • The large intestine, or the large bowel, is the last part of
the gastrointestinal tract
• The colon is much wider than the small intestine, but is also much
shorter
• The large intestine is about 5 feet (1.5 m) in length and 2.5 inches (6-7
cm) in diameter
• Divided into:
the ascending colon (including the cecum and appendix)
Cecum ( first part of large intestine )
Appendix ( accumulation of lymphatic tissue )
the transverse colon
the descending colon
the sigmoid colon
Rectum
Anus
Anatomy
3. Function
The 4 major functions of the large intestine are:
• reabsorption of water and mineral ions such as sodium
and chloride
• formation and temporary storage of faeces
• maintaining a resident population of over 500 species
of bacteria
• bacterial fermentation of indigestible materials.
Absorbs vitamins that are created by the colonic bacteria,
such as vitamin K, vitamin B12, thiamine
(B2) and riboflavin (B1)
4. Histology
• The large intestine is lined internally by a layer of mucosa. This mucosa
contains tiny indentations called the crypts of Lieberkühn. These contain
various glands and goblet cells that help in secretion and absorption of
fluids.
• goblet cells
Goblet cells are glandular simple columnar epithelial cells whose sole
function is to secrete mucin, which dissolves in water to form mucus.
5.
6. IBD
Definition
A group of chronic intestinal diseases characterized by
inflammation of the bowel. The most common types of
inflammatory bowel disease (IBD) are ulcerative colitis and Crohn’s
disease.
Ulcerative colitis: is an inflammatory bowel disease that causes
long-lasting inflammation and sores (ulcers) in the innermost lining
of your large intestine (colon) and rectum.
Crohn's disease: is an inflammation of the lining of your digestive
tract. In Crohn's disease, inflammation often spreads deep into
affected tissues. The inflammation can involve different areas of the
digestive tract, The large intestine, small intestine or both.
7. Pathogenesis:
IBD is characterized by an exaggerated and destructive mucosal
immune response
Inflammation is the final common pathway for the pathogenesis of
IBD
Both the clinical manifestations and the morphologic changes of
IBD are the result of activation of inflammatory cells:
o Initially, neutrophils
o later in the course, mononuclear cells
8. Ulcerative colitis
It is an ulceroinflammatory disease
affecting the colon, which is limited to
the mucosa and submucosa
It begins in the rectum and extends
proximally in a continuous fashion
The disease may arise at any age, with
peak incidence between ages 20 and
years
Ulcerative colitis involves the rectum
and sigmoid and may involve the
colon
With severe active disease, there is
extensive and broad-based ulceration
of the mucosa
Crohn’s disease
This disease may affect any level of the
alimentary tract
It most commonly located at the terminal ileum
It occurs at any age but the peak age of
detection is the second and third decades of life
There is involvement of the small intestine alone
in 30% of cases, of small intestine and colon in
40%, and of the colon alone in 30%
The disease is characterized by:
Sharply defined transmural involvement of the
bowel by an inflammatory process with mucosal
damage
Fissuring with formation of fistulae
9.
10. Complication:
Ulcerative colitis
Severe bleeding
A hole in the colon (perforated colon)
Severe dehydration
Liver disease (rare)
Bone loss (osteoporosis)
Inflammation of your skin, joints and eyes, and
sores in the lining of your mouth
An increased risk of colon cancer
A rapidly swelling colon (toxic megacolon)
Increased risk of blood clots in veins and arteries
Crohn's disease
Inflammation.
Bowel obstruction.
Ulcers.
Fistulas.
Anal fissure.
Malnutrition. Diarrhea, abdominal pain and
cramping
Colon cancer.
12. Anti-inflammatory drugs
Anti-inflammatory drugs are often the first step in the treatment of inflammatory bowel disease.
Aminosalicylates
Corticosteroids
Immune system suppressors
These drugs also reduce inflammation, but they target your immune system rather than directly treating
inflammation. Instead, they suppress the immune response that releases inflammation-inducing chemicals
the intestinal lining. For some people, a combination of these drugs works better than one drug alone
Azathioprine and mercaptopurine
Cyclosporine
Antibiotics
People with ulcerative colitis who run fevers will likely be given antibiotics to help prevent or
control infection. Antibiotics can reduce the amount of drainage and sometimes heal fistulas
abscesses in people with Crohn's disease.
Metronidazole
Ciprofloxacin
14. Surgery for Crohn's disease
During surgery, the doctor removes a
damaged portion of the digestive tract and
then reconnects the healthy sections.
Surgery may also be used to close fistulas and
drain abscesses.
A common procedure for Crohn's disease is
strictureplasty, which widens a segment of the
intestine that has become too narrow.
Surgery for ulcerative colitis.
Surgery can often eliminate ulcerative colitis,
but that usually means removing your entire
colon and rectum (proctocolectomy). In most
cases, this involves a procedure called ileoanal
anastomosis that eliminates the need to wear
a bag to collect stool. The surgeon constructs
a pouch from the end of the patient small
intestine. The pouch is then attached directly
to the anus, allowing the patient to expel
waste relatively normally.
In some cases, a pouch is not possible.
Instead, surgeons create a permanent opening
in the abdomen (ileal stoma) through which
stool is passed for collection in an attached
bag.