Chapter 16 - Large Intestine

Question 1

How long is the large intestine approximately in adults?

Answer 1

120-150 cm

Question 2

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?

Answer 2

Ileocecal valve

Question 3

Name the four layers of large intestine wall

Answer 3

[s] serosa
[m] muscularis
[s] submucosa
[m] mucosa

Question 4

The rectum does not have a _______ layer

Answer 4

serous layer

Question 5

The rectum and anal canal receive arterial blood from

Answer 5

the hemorrhoidal artery

Question 6

The mucosa is smooth surfaced and is arranged in folds called

Answer 6

plicae semilunares coli

Question 7

The right half of the large intestine receive arterial blood from

Answer 7

the superior mesenteric artery

Question 8

The left or lower portion of the large intestine receive arterial blood from

Answer 8

inferior mensenteric artery

Question 9

Main functions of the large intestine are:
1.
2.
3. (to a minor extent)

Answer 9

1. Storage and movement of intestinal content
2. Absorption of water, electrolyte and bile acid
3. Excretion of water, mucus, potassium and bicarbonate

Question 10

What are the 3 basic patterns of movement of the large bowel?

Answer 10

1. Periodic tonic contractions of the longitudinal and circular muscles
2. Nonpropulsive contractions eg. peristalsis and retrograde peristalsis (back and forth)
3. Spontaneous mass movements (urge to defecate when feces move into rectum)

Question 11

What is hematochezia?

Answer 11

blood in stool

Question 12

What is the name of the condition where hundreds of adenomatous polyps develop throughout the colon?

Answer 12

Familial adenomatous polyposis (FAP)

Question 13

What is the name of a hereditary syndrome where multiple adenomatous polyps develop and osteomas appear on the mandible, skull and long bones?

Answer 13

Gardner syndrome

Question 14

What are the names of 3 most common polyposis syndromes?

Answer 14

1. Familial adenomatous polyposis (FAP)
2. Gardner Syndrome
3. Peutz-Jeghers Syndrome (PJS)

Question 15

What is the name of the Syndrome characterized by multiple polyps and abnormal brown pigmentation of the lips, oral mucosa and skin?

Answer 15

Peutz-Jeghers Syndrome (PJS)

Question 16

What are the two types of ischaemic colitis?

Answer 16

1. Occlusive - mechanical obstruction eg. emboli
2. 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.

Question 17

What is the name of the disease that have ulceration in the small bowel and/ colon during the neonatal period?

Answer 17

Necrotizing enterocolitis (NEC)

Treatment: NBM, NG tube for suctioning, IV nutrition & antibiotic.

Question 18

What is the cardinal symptom occurring 70-90% of the time in UC associated usually with blood in stool?

Answer 18

Diarrhea

Question 19

What are some treatments for UC?

Answer 19

1. In adults, avoidance of food that aggravate symptoms
2. In children - nutritional therapy
3. Fibre restriction for those with strictures and lactose avoidance for those with lactose intolerance
4. Drug therapy 💊
5. Bedrest for acute exacerbation
6. Surgery - hemorrhage, perforation, carcinoma, severe colitis with or without toxic megacolon, unresponsive to medications

Question 20

What is toxic megacolon?

Answer 20

An acute dilatation of the diseased colon associated with systemic toxicity.

Note: Most severe, life threatening complication of UC

Question 21

Treatment of toxic megacolon includes:

Answer 21

1. Nill by mouth
2. NG suction
3. IV fluids and electrolytes
4. Steroids
5. Broad spectrum antibiotics
6. Surgery if no improvement within 24-48 hours

Question 22

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?

Answer 22

Pseudomembranous colitis

Question 23

What is the name of the spore-forming, gram-negative, anaerobic rod associated with pseudomembranous colitis that produces toxins?

Answer 23

Clostridium difficile (C. difficile)

Question 24

Treatment of pseudomembranous colitis inclues:

Answer 24

1. Discontinue antibiotics
2. Administrating an agent that binds the C. difficile toxin eg. cholestyramine or one that eradicates the organism altogether eg. metronidazole

Question 25

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?

Answer 25

Cow's milk protein-induced enterocolitis

Question 26

Irritable bowel syndrome (IBS), the most frequent reason for outpatient visits is characterized by:

Answer 26

abdominal pain, altered bowel habit, distention, constipation and diarrhea

Question 27

Treatment for IBS includes:

Answer 27

1. Sympathetic diagnosis and reassurance that organic causes have been ruled out 2. High fibre diet 3. Anticholinergic agents to decrease abdominal pain and diarrhea 4. Psychological support and drug therapy (to reduce stress) 5. Probiotics 6. Laxative or stimulant 7. Serotonin receptor agonists to decrease motility 8. Rifaximin for bacterial overgrowth 9. Peppermint oil relaxes smooth muscle

Question 28

Chron's disease involves the ___ ____ of the bowel wall. It is often segmental. Complications include ___ & ___.

Answer 28

Full thickness | Complications: Stricture and fistula

Question 29

What is the name of the common disorder occuring in school-aged children where intermittent abdominal pain persists for more than 3 months?

Answer 29

Chronic recurrent abdominal pain syndrome

Question 30

Can you name 3 parasitic diseases that affect the large intestine?

Answer 30

1. Amebiasis (caused by E.histoytica) 2. Trypanosomiasis (caused by T.cruzi) 3. Trichuriasis (whipworm)

Question 31

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?

Answer 31

mucous producing cells (adenocarcinoma)

Question 32

What are 3 types of intestinal obstruction?

Answer 32

1. Mechanical eg. atresia, stenosis, hernia 2. Neurogenic or Pseudo-obstruction (smooth muscle, endocrine, neurological or pharmalogical causes) 3. Vascular obstruction (emboli or atherosclerosis)

Question 33

Anorectal disorders includes:

Answer 33

1. Hemorrhoids 2. Fecal impaction 3. Encopresis 4. Abscess 5. Anal fistula 6. Anal fissure (thin tear) 7. Rectal prolapse

Question 34

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?

Answer 34

Hirschsprung's disease

Question 35

How is Hirschsprung's disease diagnosed and treated?

Answer 35

Diagnosed by: barium enema, anorectal manometry, and biopsy of the rectum Treatment: Surgery - stoma or pull-through surgery