4C A&P and Pathology of the Large Intestine Flashcards

1
Q

Which intestine is longer, small intestine or large intestine?

A

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

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2
Q

Which intestine has a larger diameter?

A

Large intestine

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3
Q

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

A

Longitudinal bands called teniae coli

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4
Q

Why are outpouchings called haustra formed between the teniae coli?

A

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

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5
Q

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

A

No!

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6
Q

What are the general parts of the large intestine?

A

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

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7
Q

What do the crypts of the large intestine contain?

A

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

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8
Q

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

A

Large intestine cells have scant microvilli

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9
Q

What do the absorptive cells of the large intestine absorb?

A

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

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10
Q

What do goblet cells do in the large intestine?

A

Secrete mucus to make it easier for stools to pass

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11
Q

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

A

Paracrine hormones

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12
Q

What are the four major functions of the large intestine?

A

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

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13
Q

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

A

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

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14
Q

Does the colon have bacteria at birth?

A

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

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15
Q

What are some of the established roles of intestinal flora?

A

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

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16
Q

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

A

The organic acids made by the colon bacteria

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17
Q

What leads to gas formation in the large intestine?

A

Fermentation of indigestible sugars

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18
Q

What are the four distinct mechanisms of diarrhea?

A

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

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19
Q

When does osmotic diarrhea occur?

A

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)

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20
Q

When does secretory diarrhea occur?

A

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

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21
Q

What causes exudative diarrhea?

A

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

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22
Q

When does diarrhea due to decreased absorption time occur?

A

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

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23
Q

What are some factors that decrease contact time?

A

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)

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24
Q

What is constipation?

A

Infrequent passage of stool

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25
Q

When does constipation increase in a person’s life?

A

With age, especially after age 65

26
Q

What drugs tend to cause constipation?

A

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

27
Q

What is irritable bowel syndrom (IBS)?

A

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

28
Q

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

A

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

29
Q

What is IBS believed to be a result of?

A

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

30
Q

What is associated with the onset of IBS?

A

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

31
Q

What is inflammatory bowel disease (IBD)?

A

Two related inflammatory intestinal disorders - Crohn disease and ulcerative colitis

32
Q

Is Crohn disease and ulcerative colitis distinguishable?

A

Yes, but they have many features in common

33
Q

What do Crohn disease and ulcerative colitis have in common?

A

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

34
Q

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

A

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

35
Q

What are Crohn disease and ulcerative colitis characterized by?

A

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

36
Q

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

A

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

37
Q

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

A

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

38
Q

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

A

Monoclonal antibody (from an animal)

39
Q

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

A

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

40
Q

What is Diverticulosis?

A

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

41
Q

What is Diverticulosis characterized by?

A

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

42
Q

What is the cause of Diverticulosis?

A

High intraluminal pressure on areas of weakness in the bowel wall

43
Q

What is Diverticulitis?

A

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

44
Q

What are the most common complaints of Diverticulitis?

A

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

45
Q

What are complications of Diverticulitis?

A

Perforation with peritonitis, hemorrhage, and bowel obstruction

46
Q

What is acute appendicitis?

A

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

47
Q

Where is the pain in acute appendicitis?

A

LRQ

48
Q

Where does the appendix dangle from?

A

The cecum.

49
Q

What can occur if swollen appendix bursts before surgery?

A

Peritonitis. Treatment w/ antibiotics becomes necessary

50
Q

What are the major mechanical causes of mechanical obstruction?

A

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)

51
Q

What kind of reflex is the defecation reflex?

A

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

52
Q

What is the defecation reflex initiated by?

A

Pressure in the sigmoid colon and the rectum

53
Q

What is the Valsalva maneuver?

A

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

54
Q

What is hematemesis?

A

Blood in the vomitus

55
Q

What does bright red blood in stools indicate?

A

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

56
Q

What is melena?

A

Passage of black or tarry stools

57
Q

What do tarry stools indicate?

A

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

58
Q

How can occult bleeding be detected?

A

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

59
Q

How common is adenocarcinoma of the colon and rectum?

A

One of the most common cancers in the Western World

60
Q

When does adenocarcinoma of the colon and rectum peak?

A

60-70 years of age

61
Q

How does adenocarcinoma of the colon and rectum begin?

A

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

62
Q

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

A

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