12. Large Intestine And Inflammatory Bowel Disease Flashcards
Give an example of a vitamin produced in the large intestine
Vitamin K by bacteria
What leads to the formation of sacculations in the large intestine? What are the saturation called?
External longitudinal muscle is incomplete, forms 3 distinct bands called teniae coli, which cause sacculations when they contract.
Sacculations are called haustra.
What features aid water absorption in the large intestine?
Apical ENaC ion channels facilitate water absorption.
Na+/K+ ATPase sets up the concentration gradient.
Tight junctions between cells are smaller, so water that has been absorbed cannot escape back into the lumen of the large intestine.
ENaC channels are induced by aldosterone.
Give 2 examples of extra-intestinal problems that can occur with an inflammatory bowel disease
MSK pain - arthritis.
Skin - erythema nodosum, pyoderma gangrenosum, psoriasis.
Liver/biliary tree - primary sclerosing cholangitis.
Eye problems.
Give 2 causes of irritable bowel disease
Genetic - first degree relative increased risk.
Gut organisms - altered interactions.
Immune response eg triggered by smoking, infections, antibiotics, diet.
How may a patient with Crohn’s disease present?
15-30 years and >60 years old. Weight loss. Right lower quadrant pain with palpable tender mass. Mild perianal inflammation/ulceration. Low grade fever. Mildly anaemic. Non-bloody frequent loose stools.
What is seen pathologically in the bowel of a patient with Crohn’s disease?
Hyperaemia. Mucosal oedema. Discrete superficial ulcers. Deeper ulcers. Transmural inflammation. Cobblestone appearance. Fistulae. Fibrosis.
What causes the cobblestone appearance of the bowel in Crohn’s?
Is caused by linear ulcers criss-crossing.
Why does Crohn’s lead to thickening of the bowel wall and narrowing of the lumen?
Repeated process of transmural inflammation and healing.
What type of chronic inflammatory cells are seen in histologies of patients with Crohn’s?
Granulomas.
Give 3 ways of investigating a patient for Crohn’s disease
Blood test - anaemia.
CT/MRI - bowel wall thickening, obstruction, extramural problems, strictures.
Barium enema/follow through - strictures/fistulae.
Colonoscopy - only of large intestine.
How may a patient with ulcerative colitis present?
Young adult.
Frequent loose bloody stools with mucus.
Weight loss.
Mild lower abdominal pain/cramping with a mildly tender abdomen.
What is seen pathologically in the bowel of a patient with ulcerative colitis?
Chronic inflammatory infiltrate of lamina propria (mucosa). Crypt abscesses - crypt distortion. Goblet cells. Pseudopolyps. Loss of haustra.
Give 3 ways of investigating a patient for ulcerative colitis
Blood test - anaemia, serum markers. Stool cultures. Plain abdominal radiographs. Barium enema - ulceration. CT/MRI - lead pipe colon due to loss of haustra. Colonoscopy.
What is indeterminate colitis?
Name given to the condition found in 10% of patients, where disorder cannot be classified, due to containing features of both Crohn’s disease and ulcerative colitis.
What layers of the intestine are affected in Crohn’s vs ulcerative colitis?
Crohn’s - all layers.
Ulcerative colitis - mucosa.
What are skip lesions?
In Crohn’s where sections of affected bowel are interjected by unaffected sections.
Give 2 ways of treating inflammatory bowel disease medically, and what is each used for?
Aminosalicylates - for flares and remission.
Corticosteroids - for flares.
Immunomodulators - for fistulae/maintained even of remission when resistant to two above.
When is surgery used as a treatment for Crohn’s?
Last resort as not curative.
Used when fistulae/strictures.
As little bowel is removed as possible.
When is surgery used as a treatment for ulcerative colitis?
Curable with a colectomy, so used if inflammation is not settling, there are precancerous changes or a toxic megacolon.
What part of the GI tract is affected in Crohn’s disease?
Anywhere from mouth to anus, but usually ileum is involved.
What part of the GI tract is affected in ulcerative colitis?
Usually begins in rectum and can spread to large intestine.
