Chapter 16 - Large Intestine Flashcards
How long is the large intestine approximately in adults?
120-150 cm
What is the name of the valve that acts as a sphincter both to control the passage of intestinal contents from the ileum to the colon AND to prevent the reflux of bacteria from colon back into the small bowel?
Ileocecal valve
Name the four layers of large intestine wall
[s] serosa
[m] muscularis
[s] submucosa
[m] mucosa
The rectum does not have a _______ layer
serous layer
The rectum and anal canal receive arterial blood from
the hemorrhoidal artery
The mucosa is smooth surfaced and is arranged in folds called
plicae semilunares coli
The right half of the large intestine receive arterial blood from
the superior mesenteric artery
The left or lower portion of the large intestine receive arterial blood from
inferior mensenteric artery
Main functions of the large intestine are:
1.
2.
3. (to a minor extent)
- Storage and movement of intestinal content
- Absorption of water, electrolyte and bile acid
- Excretion of water, mucus, potassium and bicarbonate
What are the 3 basic patterns of movement of the large bowel?
- Periodic tonic contractions of the longitudinal and circular muscles
- Nonpropulsive contractions eg. peristalsis and retrograde peristalsis (back and forth)
- Spontaneous mass movements (urge to defecate when feces move into rectum)
What is hematochezia?
blood in stool
What is the name of the condition where hundreds of adenomatous polyps develop throughout the colon?
Familial adenomatous polyposis (FAP)
What is the name of a hereditary syndrome where multiple adenomatous polyps develop and osteomas appear on the mandible, skull and long bones?
Gardner syndrome
What are the names of 3 most common polyposis syndromes?
- Familial adenomatous polyposis (FAP)
- Gardner Syndrome
- Peutz-Jeghers Syndrome (PJS)
What is the name of the Syndrome characterized by multiple polyps and abnormal brown pigmentation of the lips, oral mucosa and skin?
Peutz-Jeghers Syndrome (PJS)
What are the two types of ischaemic colitis?
- Occlusive - mechanical obstruction eg. emboli
- Nonocclusive - severe derangement in Central circulation eg. congestive heart failure, MI, hemorrhage, Sepsis or cardiac arrhythmia
Treatment: Most patients recover spontaneously, although a minority develop bowel infarction and peritonitis. These pts require resection, primary anastomosis or temporary colostomy.
What is the name of the disease that have ulceration in the small bowel and/ colon during the neonatal period?
Necrotizing enterocolitis (NEC)
Treatment: NBM, NG tube for suctioning, IV nutrition & antibiotic.
What is the cardinal symptom occurring 70-90% of the time in UC associated usually with blood in stool?
Diarrhea
What are some treatments for UC?
- In adults, avoidance of food that aggravate symptoms
- In children - nutritional therapy
- Fibre restriction for those with strictures and lactose avoidance for those with lactose intolerance
- Drug therapy 💊
- Bedrest for acute exacerbation
- Surgery - hemorrhage, perforation, carcinoma, severe colitis with or without toxic megacolon, unresponsive to medications
What is toxic megacolon?
An acute dilatation of the diseased colon associated with systemic toxicity.
Note: Most severe, life threatening complication of UC
Treatment of toxic megacolon includes:
- Nill by mouth
- NG suction
- IV fluids and electrolytes
- Steroids
- Broad spectrum antibiotics
- Surgery if no improvement within 24-48 hours
What is the name of the condition where there is acute inflammation of the bowel mucosa with the formation of pseudomembranous plaques overlying area of superficial ulceration?
Pseudomembranous colitis
What is the name of the spore-forming, gram-negative, anaerobic rod associated with pseudomembranous colitis that produces toxins?
Clostridium difficile (C. difficile)
Treatment of pseudomembranous colitis inclues:
- Discontinue antibiotics
- Administrating an agent that binds the C. difficile toxin eg. cholestyramine or one that eradicates the organism altogether eg. metronidazole
An infant up to 6 months of age manifests with vomiting, diarrhea, poor weight gain, hamatochezia and irritability to cow’s milk protein is called what condition?
Cow’s milk protein-induced enterocolitis
Irritable bowel syndrome (IBS), the most frequent reason for outpatient visits is characterized by:
abdominal pain, altered bowel habit, distention, constipation and diarrhea
Treatment for IBS includes:
- Sympathetic diagnosis and reassurance that organic causes have been ruled out
- High fibre diet
- Anticholinergic agents to decrease abdominal pain and diarrhea
- Psychological support and drug therapy (to reduce stress)
- Probiotics
- Laxative or stimulant
- Serotonin receptor agonists to decrease motility
- Rifaximin for bacterial overgrowth
- Peppermint oil relaxes smooth muscle
Chron’s disease involves the ___ ____ of the bowel wall. It is often segmental. Complications include ___ & ___.
Full thickness
Complications: Stricture and fistula
What is the name of the common disorder occuring in school-aged children where intermittent abdominal pain persists for more than 3 months?
Chronic recurrent abdominal pain syndrome
Can you name 3 parasitic diseases that affect the large intestine?
- Amebiasis (caused by E.histoytica)
- Trypanosomiasis (caused by T.cruzi)
- Trichuriasis (whipworm)
Colorectal cancer is the second most common cancer (apart from melanoma of the skin) in adults after prostate cancer in men and breast cancer in women. Approximately 95% of the intestinal cancer occur where?
mucous producing cells (adenocarcinoma)
What are 3 types of intestinal obstruction?
- Mechanical eg. atresia, stenosis, hernia
- Neurogenic or Pseudo-obstruction (smooth muscle, endocrine, neurological or pharmalogical causes)
- Vascular obstruction (emboli or atherosclerosis)
Anorectal disorders includes:
- Hemorrhoids
- Fecal impaction
- Encopresis
- Abscess
- Anal fistula
- Anal fissure (thin tear)
- Rectal prolapse
What is the name of the condition when a newborn have difficulty passing stool because there is a congenital absence of part or all of the nerve cells in the colon?
Hirschsprung’s disease
How is Hirschsprung’s disease diagnosed and treated?
Diagnosed by: barium enema, anorectal manometry, and biopsy of the rectum
Treatment: Surgery - stoma or pull-through surgery
