4C A&P and Pathology of the Large Intestine

Question 1

Which intestine is longer, small intestine or large intestine?

Answer 1

Small intestine is longer, however, the large intestine has a larger diameter though it is only about 5 feet long

Question 2

Which intestine has a larger diameter?

Answer 2

Large intestine

Question 3

What are the fibers of the external muscular layer of the large intestine collected into?

Answer 3

Longitudinal bands called teniae coli

Question 4

Why are outpouchings called haustra formed between the teniae coli?

Answer 4

B/c teniae bands are shorter than the rest of the colon

Question 5

Are there any villi in the mucosa of the large intestine?

Answer 5

No!

Question 6

What are the general parts of the large intestine?

Answer 6

Cecum, ascending colon, hepatic flexure, transverse colon, splenic flexure, descending colon, sigmoid colon, and rectum

Question 7

What do the crypts of the large intestine contain?

Answer 7

Absorptive cells, goblet cells, endocrine cells, and regenarative cells

Question 8

How do the large intestine cells compare to the small intestine cells?

Answer 8

Large intestine cells have scant microvilli

Question 9

What do the absorptive cells of the large intestine absorb?

Answer 9

Mainly water, and may absorb some vitamins that are made by bacteria

Question 10

What do goblet cells do in the large intestine?

Answer 10

Secrete mucus to make it easier for stools to pass

Question 11

What type of endocrine hormones are secreted in the large intestine?

Answer 11

Paracrine hormones

Question 12

What are the four major functions of the large intestine?

Answer 12

Propulsion and storage of unabsorbed material
Place of residence for flora
Absorption of small amounts of water and electrolytes
Defecation

Question 13

Do we have any normal bacteria in the large intestine? Small intestine?

Answer 13

Large intestine has a complex family of bacteria about 500 species.
Small intestine has some bacteria but not nearly as much as the large intestine

Question 14

Does the colon have bacteria at birth?

Answer 14

No, it is sterile. But the intestinal bacteria flora becomes established early in life

Question 15

What are some of the established roles of intestinal flora?

Answer 15

Fermentation of undigestable dietary fiber to generate FAs, which are a major nutritional source for the colon and have trophic effects that promote normal mucosal growth and development.
Creation of inhospitable environment to pathogenic organisms
Metabolism of various compounds - bile salts and certain drugs.
Creation of vitamin K, B12, and Folic Acid

Question 16

What is responsible for the slightly acidic nature of stools (pH 5.0 to 7.0)?

Answer 16

The organic acids made by the colon bacteria

Question 17

What leads to gas formation in the large intestine?

Answer 17

Fermentation of indigestible sugars

Question 18

What are the four distinct mechanisms of diarrhea?

Answer 18

Increased osmotic load.
Increased secretion of fluid into the LI
Inflammation of LI lining
Decreased absorption time (very very fast motility) - too fast for water to be absorbed in the colon

Question 19

When does osmotic diarrhea occur?

Answer 19

When you have something in the gut that is not absorbable and it attracts a lot of water. E.g, lactose intolerance, poorly absorbed salts, or large ingestion of hexitols (sorbitol)

Question 20

When does secretory diarrhea occur?

Answer 20

When the small and large bowel secrete more electrolytes and water than they absorb. Caused by bacterial toxins such as from cholera, enteropathetic viruses, bile salts and unabsorbed dietary fat

Question 21

What causes exudative diarrhea?

Answer 21

Several mucosal diseases that cause mucosal inflammation, ulceration, or tumefaction - resultant outpouring of plasma, serum proteins, blood, and mucus increases fecal bulk and fluid content

Question 22

When does diarrhea due to decreased absorption time occur?

Answer 22

When chyme is not in contact with an adequate absorptive surface of the GI tract for a long enough time so that too much water remains in the feces

Question 23

What are some factors that decrease contact time?

Answer 23

Small or large-bowel resection, gastric resection, vagotomy, surgical bypass of intestinal segments, and drugs that speed transit by stimulating intestinal smooth muscle (as a side effect)

Question 24

What is constipation?

Answer 24

Infrequent passage of stool

Question 25

When does constipation increase in a person's life?

Answer 25

With age, especially after age 65

Question 26

What drugs tend to cause constipation?

Answer 26

Opiates, anti-cholinergics, calcium channel blockers, diuretics, iron supplements, and aluminum antacids

Question 27

What is irritable bowel syndrom (IBS)?

Answer 27

A functional GI disorder characterized by a variable combination of chronic and recurrent intestinal symptoms not explained by structural or biochemical abnormalities

Question 28

Evidence suggest that what percentage of people in the Western countries have IBS?

Answer 28

10-20%, but most don't seek medical attention

Question 29

What is IBS believed to be a result of?

Answer 29

Dysregulation of intestinal motor and sensory functions modulated by the CNS. Tends to be increased by psychological and physiologic stress

Question 30

What is associated with the onset of IBS?

Answer 30

Menarche (first menstrual cycle, female puberty), women experience exacerbation of symptoms during the pre-menstrual period - suggesting a hormonal component

Question 31

What is inflammatory bowel disease (IBD)?

Answer 31

Two related inflammatory intestinal disorders - Crohn disease and ulcerative colitis

Question 32

Is Crohn disease and ulcerative colitis distinguishable?

Answer 32

Yes, but they have many features in common

Question 33

What do Crohn disease and ulcerative colitis have in common?

Answer 33

Inflammation of the bowel, both lack confirming evidence of a proven causative agent, and both can be accompanied by systemic manifestations

Question 34

What are Crohn disease and ulcerative colitis ultimately the result of?

Answer 34

Activation of inflammatory cells with elaboration of inflammatory mediators that cause non-specific tissue damage

Question 35

What are Crohn disease and ulcerative colitis characterized by?

Answer 35

Remissions and exacerbations of diarrhea, fecal urgency, and weight loss. Acute complications such as intestinal obstruction may develop during periods of fulminant disease.

Question 36

With IBD, which regions of the gut are affected for Crohn disease and for ulcerative colitis?

Answer 36

Crohn disease - the ileum and/or colon are affected. In ulcerative colitis ONLY the colon is affected.

Question 37

How does the tissue lining in Crohn disease differ from ulcerative colitis?

Answer 37

Crohn has a cobble-stone appearance - and thickening. Ulcerative colitis has lots of ulcers, bleeding - and thinning of the intestinal wall.

Question 38

What does any drug that ends in -mab mean? eg - adalimumab

Answer 38

Monoclonal antibody (from an animal)

Question 39

What is the manifestation of Crohn disease in the oral cavity?

Answer 39

Cobble-stone appearance of buccal mucosa. Diffuse labial, gingival or mucosal swelling. May preceded intestinal involvement. Occurs in 8-29% of pts

Question 40

What is Diverticulosis?

Answer 40

When the mucosal layer of the colon herniates thru the muscularis layer

Question 41

What is Diverticulosis characterized by?

Answer 41

Presence of diverticula in the colon (usually sigmoid colon) and generally asymptomatic

Question 42

What is the cause of Diverticulosis?

Answer 42

High intraluminal pressure on areas of weakness in the bowel wall

Question 43

What is Diverticulitis?

Answer 43

When diverticula become inflammed, no longer just Diverticulosis (which is usually asymptomatic)

Question 44

What are the most common complaints of Diverticulitis?

Answer 44

Pain in LLQ, nausea, vomiting, tenderness in LLQ, slight fever, elevated WBC count

Question 45

What are complications of Diverticulitis?

Answer 45

Perforation with peritonitis, hemorrhage, and bowel obstruction

Question 46

What is acute appendicitis?

Answer 46

Inflammation of the veriform appendix due to an obstruction with stool or a twisting of the organ or its blood supply

Question 47

Where is the pain in acute appendicitis?

Answer 47

LRQ

Question 48

Where does the appendix dangle from?

Answer 48

The cecum.

Question 49

What can occur if swollen appendix bursts before surgery?

Answer 49

Peritonitis. Treatment w/ antibiotics becomes necessary

Question 50

What are the major mechanical causes of mechanical obstruction?

Answer 50

Herniation of a segment in umbilical or inguinal regions. Adhesion b/w loops of intestine Volvulus (twisting of intestine) Intussusception (piece of intestine that folds back on itself - like a hose within a hose)

Question 51

What kind of reflex is the defecation reflex?

Answer 51

Spinal-cor mediated parasympathetic reflex - causes the walls of the sigmoid colon and the rectum to contract and the internal anal sphincter to relax

Question 52

What is the defecation reflex initiated by?

Answer 52

Pressure in the sigmoid colon and the rectum

Question 53

What is the Valsalva maneuver?

Answer 53

Voluntary aiding of defecation by closing the glottis and contracting our diaphragm and abdominal muscles

Question 54

What is hematemesis?

Answer 54

Blood in the vomitus

Question 55

What does bright red blood in stools indicate?

Answer 55

Bleeding is from the lower bowel. When it coats the stool it is often the result of bleeding hemorrhoids

Question 56

What is melena?

Answer 56

Passage of black or tarry stools

Question 57

What do tarry stools indicate?

Answer 57

Source of bleeding is above the level of the ileocecal valve, although this is not always the case

Question 58

How can occult bleeding be detected?

Answer 58

Only way is by chemical means. Can be caused by gastritis, peptic ulcer, or lesions of the intestine

Question 59

How common is adenocarcinoma of the colon and rectum?

Answer 59

One of the most common cancers in the Western World

Question 60

When does adenocarcinoma of the colon and rectum peak?

Answer 60

60-70 years of age

Question 61

How does adenocarcinoma of the colon and rectum begin?

Answer 61

Formation of polyps (looks like a single cobble stone) - a tissue that is dangling somewhere from the colon wall. Could be metastatic

Question 62

What are predisposing factors for adenocarcinoma of the colon and rectum?

Answer 62

Polyps, long-standing UC, genetic factors, and low fiber, high animal fat diet