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Digestive Systems 3 > 15. Anat, Phys, and Path of Large Intestine > Flashcards

15. Anat, Phys, and Path of Large Intestine Flashcards

1
Q
  1. 4 Differentiate between the different sections of the large intestine
    - What are the names of the different sections of the large intestine?
A

Appendix, Cecum, Ascending colon, Hepatic flexure, Transverse colon, Splenic flexure, Descending colon, Sigmoid colon, Rectum

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2
Q
  1. 4 Differentiate between the different sections of the large intestine
    - The fibers of its external muscular layer are collected into longitudinal bands called?
    - Because these bands are shorter than the rest of the colon, the colon wall forms outpouchings called?
    - Are villi present on the mucosa?
A

Longitudinal bands: teniae coli

Outpouchings: haustra

No villi found

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3
Q

15.5 What cells are found in the Crypts of Lieberkuhn in the large intestine?

A
  1. Absorptive cells (small amounts of water and electrolytes)
  2. Goblet cells
  3. Endocrine cells
  4. Regenerative cells
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4
Q
  1. 7 List and explain the four functions of the large intestine
    - Propulsion and storage of what?
    - Place of residence of what?
    - Absorption of what?
    - #4
A
  1. Propulsion & storage of unabsorbed material
  2. Place of residence for flora (bacteria)
  3. Absorption of small amounts of water and electrolytes
  4. Defecation
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5
Q
  1. 8 List the functions of intestinal flora
    - Fermentation of what?
    - Creation of what kind of environment?
    - Metabolism of what?
    - Creation of what chemicals?
A
  1. Fermentation of undigestible dietary fiber to generate fatty acids (nutrition and trophic effects)
  2. Creation of an environment inhospitable to pathogenic microorganisms (preventing colonization)
  3. Metabolism of various compounds (bile salts, drugs)
  4. Creation of vitamin K, B12, and folic acid
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6
Q

15.8 Explain the three puroposes of fermentation of undigestible dietary fiber in the large intestine

A

The fermentation generates fatty acids. The fatty acids have three functions:

  1. Serve as major nutritional source for the colon
  2. Have trophic effects to promote normal mucosal growth and development
  3. Causes slightly acidic nature of stools (pH 5.0-7.0)

(Also can lead to gas formation)

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7
Q

15.9 Explain how the large intestine can create an environment that is inhospitable to pathogenic microorganisms and prevent colonization of the GI tract

A

Mechanism not completely understood, but factors include:

  1. Simple crowding
  2. pH (Many pathogens favor a neutral or more alkaline environment)
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8
Q

15.9 The intestinal flora will create vitamin K, B12, and folic acid. What do these vitamins do?

A

Vitamin K - essential to liver for efficient synthesis of certain blood clotting factors (prothrombin, VII, IX & X)
Vitamin B12 and folic acid - important for final maturation of erythrocytes

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9
Q

15.10 What are the four distinct mechanisms of diarrhea?

A
  1. Increased osmotic load
  2. Increased secretion
  3. Inflammation
  4. Decreased absorption time
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10
Q
  1. 11 Explain the etiology of osmotic diarrhea
    - Occurs when _________, _________ solutes remain in the bowel?
    - What are examples of these types of solutes?
A

Unabsorbable, water-soluble solutes - they retain water in the stool

Examples:

  1. Sugar intolerance - Lactose intolerance (lactase)
  2. Poorly absorbed salts - Mg sulfate or Na phosphate (used as laxatives or antacids)
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11
Q
  1. 11 How does ingestion of hexitols (sugar substitutes) cause osmotic diarrhea - “chewing gum” or “diatetic food” diarrhea?
    - What are two examples of hexitols?
A

Cause osmotic diarrhea as a result of their slow absorption and stimulation of rapid small-bowel motility

Sorbitol and mannitol

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12
Q
  1. 12 Explain the etiology of secretory diarrhea

- What are the conditions for it to occur?

A

Occurs when small and large bowel secrete more electrolytes and water than they absorb

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13
Q

15.12 What are examples of some secretagogues that cause secretory diarrhea?

(Secretagogues - something that stimulates secretion)

A
  1. Bacterial toxins (in cholera)
  2. Enteropathogenic viruses
  3. Bile acids
  4. Unabsorbed dietary fat
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14
Q

15.13 What are examples of mucosal diseases that can cause exudative diarrhea?

What conditions do they all cause?

A

Regional enteritis, ulcerative colitis, lymphoma cancer

They all cause mucosal inflammation, ulceration, or tumefaction (puffing/swelling)

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15
Q
  1. 13 Exudative diarrhea
    - The mucosal inflammation, ulceration, or tumefaction causes an outpouring of what?
  • Involvement of the recetal mucosa may cause what?
A

They cause an outpouring of plasma, serum proteins, blood, and mucus which increases fecal bulk and fluid content.

Involvement of the recetal mucosa may cause urgency and increased stool frequency because the inflamed rectum is more sensitive to distention.

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16
Q

15.14 How does decreased absorption time lead to diarrhea?

A

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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17
Q
  1. 14 What are factors that decrease absorption time / contact time?
    - Resections of structures?
    - Surgical bypass of what?
    - Drugs which do what as a side effect?
A
  1. Small or large bowel resection
  2. Gastric resection
  3. Vagotomy (resection of vagus nerve)
  4. Surgical bypass of intestinal segments
  5. Drugs that speed transit by stimulating intestinal smooth muscle (as a side effect)
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18
Q
  1. 15 Define constipation

- What is the difficulty with this definition?

A

Constipation - infrequent passage of stools

Difficulty arise from the many individual variations of function that are normal (what is normal varies and age is a huge factor)

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19
Q

15.16 What are some common causes of constipation?

A
  1. Failure to respond to the urge to defecate
  2. Inadequate fiber or fluid intake
  3. Weakness of the abdominal muscles
  4. Inactivity and bed rest
  5. Pregnancy
  6. Hemorrhoids
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20
Q

15.16 What are some disorders associated with chronic constipation?

A
  1. Neurologic diseases (spinal cord injury, Parkinson’s, MS)
  2. Endocrine disorders (hypothyroidism, diabetic neuropathy)
  3. Obstructive lesions in the GI tract
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21
Q

15.16 What drugs are associated with chronic constipation?

A
  1. Opiates
  2. Anti-cholinergic agents
  3. Calcium channel blockers
  4. Diuretics
  5. Iron supplements
  6. Aluminum antacids
22
Q
  1. 17 Define irritable bowel syndrome
    - Combination of what symptoms?
    - Not explained by what kind of abnormalities?
A

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

23
Q

15.18 What is believed to be the cause of irritable bowel syndrome?

A

Believed to result from dysregulation of intestinal motor and sensory functions modulated by the CNS

People with IBS tend to experience increased motility and abnormal intestinal contractions in response to psychological and physiologic stress

24
Q

15.18 What is a hallmark of irritable bowel syndrome?

A

Abdominal pain that is relieved by defecation and associated with a change in consistency or frequency of stools

25
Q

15.18 What are the characteristic syndromes of irritable bowel syndrome?

A

Persistent or recurrent symptoms of:

  1. Abdominal pain
  2. Altered bowel function
  3. Varying complaints of flatulence, bloatedness, nausea and anorexia, constipation or diarrhea, and anxiety or depression
26
Q

15.19 Although the role that psychological factors in IBS is not certain, what are some factors of note?

A
  1. Women > men
  2. Menarche associated with onset of IBS (first menstrual cycle)
  3. Women notice exacerbation of symptoms during pre-menstrual period (possible hormone)
27
Q

15.20 IBS is used to designate what two related inflammatory intestinal disorders?

A

Crohn’s disease and ulcerative colitis

28
Q

15.20 What features do Crohn’s disease and ulcerative colitis have in common?

A
  1. Both produce bowel inflammation
  2. Both lack confirming evidence of a proven causative agent
  3. Both can be accomplished by systemic manifestations
29
Q
  1. 21 Clinical manifestations of Crohn’s disease and ulcerative colitis (IBS related)
    - Activation of what cells and what mediators?
A

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

30
Q
  1. 21 Clinical manifestations of Crohn’s disease and ulcerative colitis
    - Both diseases characterized by what?
A

Characterized by remissions and exacerbations of diarrhea, fecal urgency, and weight loss

Acute complications (like intestinal obstruction) may develop during periods of fulminant (sudden, intense) disease

31
Q
  1. 22 What is diverticulosis?

- Herniation of what layers?

A

Condition in which the mucosal layer of the colon herniates through the muscularis layer

32
Q
  1. 22 Diverticulosis

- Characterized by the presence of what in the colon?

A

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

33
Q
  1. 22 Diverticulosis

- Results from what pressure?

A

High intraluminal pressure on areas of weakness in the bowel wall

34
Q
  1. 23 What is diverticulitis?

- Complications include?

A

Inflammation of the diverticula

Complications include perforation with peritonitis, hemorrhage, and bowel obstruction

35
Q
  1. 23 What are five common complaints of diverticulitis?
    - Pain where?
    - Tenderness where?
    - Elevated what?
    - Two others
A
  1. Pain in lower left quadrant
  2. Tenderness in lower left quadrant
  3. Elevated white blood cell count
  4. Nausea and vomiting
  5. Slight fever
36
Q
  1. 24 Define acute appendicitis
    - Inflammation of what organ?
    - Due to what two possible causes?
A

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

37
Q

15.24 What are symptoms of acute appendicitis?

A

Pain on lower right quadrant
Fever
Rebound tenderness

38
Q
  1. 25 How can peritonitis result from acute appendicitis?

- What kind of drug treatment becomes necessary?

A

Peritonitis can occur if swollen appendix bursts before surgery
- Treatment with antibiotics becomes necessary

39
Q
  1. 26 What are four major mechanical causes of intestinal obstruction?
    - Herniation where?
    - Adhesion between what?
    - Complete twisting
    - Invagination
A
  1. Herniation of a segment in the umbilical or inguinal regions
  2. Adhesion between loops of intestine
  3. Volvulus (complete twisting of intestine)
  4. Intussusception (intestine becomes invaginated within itself)
40
Q
  1. 27 What is the defecation reflex?

- Distention of what?

A

Distention of the rectum with feces initiates reflex contractions of its musculature and the desire to defecate

41
Q
  1. 27 Defecation reflex
    - PNS or SNS?
    - How are the Sigmoid colon, rectum, and internal anal sphincter affected?
A

Spinal cord-mediated PNS reflex

Causes wall of sigmoid colon and rectum to contract and Internal anal sphincter (smooth muscle) to relax

42
Q

15.27 As feces are forced into the anal canal, electrical signals reach the brain allowing us to decide what?

A

Allowing us to decide whether the external anal sphincter (skeletal muscle) should relax and remain open or be constricted to stop the passage of feces temporarily

43
Q

15.27 During defecation, the muscles of the rectum contract to expel feces. How do we voluntarily aid this process?

A

Valsalva maneuver

- We close the glottis and contract our diaphragm and abdominal muscles

44
Q

15.28 What can GI tract bleeding result from?

A
  1. Disease/trauma to GI structures (peptic ulcer)
  2. Blood vessel abnormalities (esophageal varices, hemorrhoids)
  3. Disorders in blood clotting
45
Q

15.28 What is hematemesis?

A

Blood in vomit - may be bright red or have a “coffee-ground” appearance because of digestive enzyme action

46
Q

15.29 What does bright red blood indicate about where bleeding is?

A

Indicates that bleeding is from the lower bowel

When it coats the stool, often the result of bleeding hemorrhoids

47
Q
  1. 29 What does black and tarry stools indicate about where bleeding is?
    - What does melena mean?
A

Indicate that source of bleeding is above the ileocecal valve level

Melena - “black” - refers to passage of black/tarry stool

48
Q
  1. 29 What can cause occult (hidden) blood?

- How can it be detected?

A

Caused by gastritis, peptic ulcer, or lesions of intestine

Detected by chemical means

49
Q

15.30 What is one of the most common cancers in the Western world?

What is the normal progression of this cancer?

A

Adenocarcinoma of the colon and rectum

Normal mucosa -> polyp -> cancer -> metastatic tumor

50
Q

15.30 What are four predisposing factors of adenocarcinoma of the colon and rectum?

A
  1. Polyps
  2. Long standing UC (ulcerative colitis - inflammation)
  3. Genetic factors
  4. Low fiber, high animal fat diet

Digestive Systems 3 (3 decks)

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