CHAPTER 29DISORDERS OF GASTROINTESTINALFUNCTION

Essentials of Pathophysiology

PRE LECTURE QUIZ TRUE/FALSE Two of the major causes of gastric irritation and

ulcer formation are aspirin or nonsteroidal anti-inflammatory drugs (NSAIDs) and infection with Helicobacter pylori.

A peptic ulcer affects only a single layer of the stomach or duodenum.

Clostridium difficile and Escherichia coli are two types of viral infections that affect the gastrointestinal system.

Small-volume diarrhea is usually painless and watery and without blood or pus in the stool. 

Appendicitis, a condition in which the appendix becomes inflamed, swollen, and gangrenous, is very uncommon.

T

F

F

F

F

PRE LECTURE QUIZ __________ refers to difficulty in swallowing. Crohn disease and ulcerative colitis are two

related intestinal disorders that fit under the category of __________ bowel disease.

__________ is a condition that occurs primarily in the sigmoid colon, in which the mucosal layer of the colon herniates through the muscular layer.

__________ disease is an immune-mediated disorder triggered by ingestion of gluten-containing grains (including wheat, barley, and rye).

__________ is a common characteristic of both ulcerative colitis and Crohn disease.

Celiac

Diarrhea

Diverticulosis

Dysphagia

inflammatory

THE JOB OF THE BOWEL To digest food: involves a corrosive

solution and potentially pathogenic bacteria

To absorb the food into the blood while keeping the corrosive substances and the bacteria inside the gut

To keep the solution moving down the bowel at the right rate for digestion and absorption

INFLAMMATION AND DAMAGE TO THE BOWEL WALL

• Hemorrhage anemia• Perforation peritonitis• Decreased mucosal function

malabsorption• Decreased bacterial containment

sepsis

HEMORRHAGE Hemorrhage above the stomach: frank

hematemesis Hemorrhage into the stomach with partial

digestion of blood: coffee-grounds vomitus Hemorrhage in the intestine with blood

mixing into stools: occult blood Hemorrhage into the intestine with large

volumes of blood: melena Hemorrhage in the rectum: red blood

coating stools

THE VICIOUS CIRCLE: ONE KIND OF BOWEL PROBLEM CAN CAUSE ANOTHER

Inflammationand cell damage

Obstruction

Malabsorption

Reflex paralysis

Distension, ischemia

Decreased bowelfunction

Food does not pass through bowel at correct rate

QUESTION

Which symptom accompanies hemorrhage into the stomach?

a. Hematemesis-b. Occult blood – c. Coffee-grounds vomitus – d. Melena -

the vomiting of blood

blood in the stool

blood mixed w/ chime

black, tarry, bloody stools, usually resulting from a hemorrhage in the alimentary tract.

ANSWER

c. Coffee-grounds vomitus Rationale: Coffee-grounds vomitus is a

classic symptom of blood in the stomach (it mixes with chyme to give it the coffee-grounds color and consistency). Hematemesis occurs in hemorrhage above the stomach; occult blood is the result of blood mixing with stool in the small intestine; and melena occurs with large-volume hemorrhages in the intestine.

DISORDERS OF THE ESOPHAGUS Dysphagia - Achalasia -

Esophageal diverticulum - Gastroesophageal reflux

disease

Cancer of the esophagus -

inability of a circular muscle to relax, resulting in widening of the structure above the muscular constriction

difficulty in swallowing

mucosal layer herniated through the muscularis layer

a chronic condition in which acid from the stomach flows back into the lower esophagus, causing pain or tissue damage

malignant neoplasm

DISORDERS OF THE STOMACH Acute gastritis Chronic gastritis Ulcer disease

Peptic ulcer Zollinger-Ellison syndrome

Stress ulcers

Cancer of the stomach

a condition in which a gastrin-secreting tumor of the pancreas or small intestine causes excessive secretion of gastric juice, leading to intractable peptic ulcers

Acute peptic ulcers occurring in association with various other pathologic conditions

erosion of the mucous membrane caused in part by the corrosive action of the gastric juice

inflammation of the stomach, especially of the mucous membrane of the stomach

SCENARIO

Mrs. D. has pain in her stomach at night and vomits up blood.

She is pale and weak The doctor finds that her hematocrit is low Her blood contains large, pale

erythrocytes and some reticulocytes Bilirubin levels are normalQuestion: Explain her symptoms

HELICOBACTER PYLORI

• The major cause of ulcers

• Second most common cause is NSAIDs

H. pylori

damages stomach

lining

ULCER repair and healing

increased risk of gastric cancer

HELICOBACTER PYLORI

“In the US: The frequency of HP infection may be linked to race. White persons account for 29% of cases, and Hispanic persons account for 60% of cases.”

“Internationally: … At least half of all people are infected … HP may be detected in approximately 90% of individuals with peptic ulcer disease...”

(Santacroce, L., and Miragliotta, G. 2005. Helicobacter pylori infection. eMedicine. Retrieved April 2005 from http://www.emedicine.com/med/topic962.htm#top.)

Helicobacter Pylori

INFLAMMATIONS OF THE SMALL AND LARGE INTESTINES

Infectious enterocolitis Viral infections Bacterial infections

Inflammatory bowel disease Crohn disease Ulcerative colitis

Diverticular disease Appendicitis

Crohn’s disease – an autoimmune condition-a chronic inflammatory bowel disease that causes scarring and thickening of the intestinal walls and frequently leads to obstruction.

DISCUSSION

Think back to the last time you had enterocolitis.

Questions: List the things that happened to you Which of them were systemic signs

of inflammation? Which of them were caused by your

sympathetic system? Which of them helped you get over

the disease? Which of them could have caused

serious complications? Why?

QUESTION

Which intestinal disorder is an autoimmune disease?

a. Enterocolitisb. Crohn diseasec. Ulcerative colitisd. Diverticulitis

ANSWER

b. Crohn diseaseRationale: Crohn disease is an

autoimmune disorder that affects the mucous membrane lining of the bowel (it gets thicker and doesn’t function as it should), causing chronic malabsorption.

ENTEROCOLITIS

The bowel attempts to get rid of the infectious agent Exudate to dilute toxins Hypermotility

Vomiting Decreased intestinal function

Food not absorbedº Osmosis draws water into the bowel

º Osmotic (or explosive) diarrhea

INFLAMMATIONS THAT CANNOT BE EXPELLED

Pain and sympathetic nervous stimulation cause the bowel to freeze in position Reflex paralysis or paralytic ileus

Muscles of the abdominal wall tighten to protect the inflamed bowel Board-like abdomen

Diaphragm and accessory breathing muscle movements decrease Shallow breathing

ONE KIND OF BOWEL PROBLEM CAN CAUSE ANOTHER

Inflammationand cell damage

Obstruction Reflex paralysis

Distension, ischemia

INTESTINAL OBSTRUCTION

Mechanical Severe, colicky pain Borborygmus Audible, high-pitched peristalsis;

peristaltic rushes Awareness of intestinal movements

Paralytic Continuous pain Silent abdomen

RESULTS OF OBSTRUCTION

Vomiting fluid and electrolyte loss

Fluids move into intestinal contents

Gas accumulates Distension of bowel Compartment

syndrome ischemia, necrosis

Anaerobic bacteria produce endotoxin toxemia

QUESTION

Tell whether the following statement is true or false.

Paralytic intestinal obstruction causes audible paralysis.

ANSWER

FalseRationale: Mechanical obstruction

results in high-pitched peristalsis (bowel sounds); in paralytic obstruction, bowel sounds are inaudible (silent abdomen).

BOWEL DISTENSION AND COMPARTMENT SYNDROME

The blood vessels on the surface of the gut are covered and held in place by the inflexible peritoneum

When the gut lumen distends, it crushes the blood vessels between the gut wall and the peritoneum

Peritoneum = Serosa

COMPARTMENT SYNDROME

• An organ expands inside a membrane that will not expand

• The blood vessels feeding the organ are crushed between the organ and the membrane

• Blood supply is cut off

SCENARIO

Mrs. K. presents with acute abdominal pain.• She has a distended, board-like abdomen with no

bowel sounds. Blood pressure is low and heart rate elevated. Her skin is pale and cool with cold sweat. She is very restless and complains of acute abdominal pain.

• The pain came on over the last 8 hours. WBC count is elevated. Now she complains of nausea and begins throwing up, but there is no blood in her vomitus. She has had no bowel movements or urine production.

Question:• What adaptive responses and counterattacks are

evident?

SCENARIO (CONT.)

• Mrs. K. has begun to run a fever• Her skin is now flushed and warm, and her

abdomen is further distended • Her blood pressure has decreased further• The doctor has ordered nasogastric suction and

an isotonic IVQuestion:• Why are you taking fluids out of her GI tract and

putting them into her veins?