ePathoPlusPage

Gastrointestinal

Outline

A. Dysphagia
    1. three phases to swallowing
        a. voluntary phase
            1. disorders assoc. with upper motor neuron lesion

        b. pharyngeal phase
            1.disorders assoc. with
                 Dx or trauma to cranial nerves V, IX, X, 

                Dx that affect swallowing center in brain (polio
                encephalitis)

                Dx affecting neuromuscular transmission (myasthenia,
                botulism)

c. esophageal  phase
    1. disorders can be either
                a. obstructive in origin

        b. motor in origin

    2. Achalasia
        a. condition in which there is an absence of peristalsis in the
         esophagus and the LES fails to relax following normal deglutition

B. Disorders of the Esophagus
    1. esophageal diverticulum

    2. esophageal varices

    3. esophageal tumors

    4. diaphragmatic hernias (hiatal hernias)

C. Gastroesophageal Reflux Disease (GERD)
    1. most common disorder of GI tract
    2. most frequent symptom is heartburn, occurring  30 - 60 minutes after
eating
    3.caused when partially digested food from stomach (high in HCL)
        refluxes into esophagus

    4. causes
        a. incompetent LES (either idiopathic or due to collagen
            vascular Dx)

        b. factors which can decrease pressure in LES
            1. foods high in fat
            2. anticholinergics
            3. caffeine
            4. theobromine (found in chocolate)
            5. alcohol
            6. smoking

        c. factors which can increase upward pressure against LES 
    (increased abdominal pressure)
    1. obesity
     2. pregnancy
    3. ascites

D. Peptic Ulcer Disease
    1. Comparison of Gastric Ulcer to Duodenal Ulcer

2. Zollinger Ellison Syndrome
  a. tumor of the pancreas causes increased gastric acid secretion

3. role of Helicobacter pylori

4. medical treatment
    a. antacids

    b. H2  receptor inhibitors

            c. proton pump inhibitors

5. surgical treatment
    a. Billroth I, (gastoduodenostomy), 
    b. Billroth II (gastojejunostomy)
            c. purposes of gastric surgery for ulcer patients
                1. prevent ulcer re-occurrence
                    a. facilitate enterogastric regurgitation
                    b. decrease secretory capacity of stomach
                    c. remove stimulus for HCL acid secretion

                2. remove complications

E. Gastritis
    1. Acute

    2. Chronic
        a. not considered to be an aftermath of acute gastritis, nor
            associated with ingestion of irritants

        b. frequent forerunner of gastric carcinoma
        c. high incidence in alcoholics
        d. symptoms = dyspepsia, diarrhea, bleeding, vomiting ( similar
            to symptoms of gastric ulcer, but no relief with administration
            of antacids)

        e. chronic iron deficiency - pernicious anemia

F. Intestinal Obstruction
    1. can be either mechanical causes or paralytic causes (paralytic ileus)
        a. mechanical
            1. tumor, stricture, adhesions
            2. hernia
            3. volvulus
    4. intussusception
b. paralytic
    1. anesthesia
     2. inflammation (esp. peritonitis)
     3. ischemia of bowel
     4. hypokalemia

2. obstruction  leads to increased distention (as bacteria continue to
             digest food and release gas as byproduct) - distention increases
             capillary permeability (causing loss of fluid and protein into gut),   
             constricts blood vessels (leading to possible bowel infarction) and
             may cause rupture (leading to peritonitis).

        3. Four cardinal manifestations of Complete SBO (small
            bowel obstruction)

            a. pain
            b. vomiting
            c. constipation
            d. distention

G. Malabsorption Syndrome
1. Etiology
   a. altered digestion  ( lack of digestive enzymes) (e.g. subtotal
                 gastrectomy, pancreatic insufficiency, liver disease or biliary
                 obstruction)

   b. altered cell transport (e.g lactase deficiency, Crohn's Dx., celiac
                 Dx, drugs, radiation)

   c. altered lymph/blood transport (e.g. radiation, lymphatic
                 obstruction, altered blood supply)

2. clinical  picture
   a. steatorrhea (excessive loss of fat in stools)
   b. wgt loss, weakness, fatigue, anorexia
   c. vitamin deficiencies
   d. protein deficiencies

3. Adult Lactase Deficiency
    a. without enzyme lactase, lactose remains in gut, osmotic pull of
             this large molecule draws water into lumen (diarrhea) and allows
             for increased action of bacteria (gas)

4. Celiac Disease (gluten enteropathy)
   a. due to intolerance to the gluten fraction of wheat or rye

   b. causes an atrophy of the intestinal villi and microvilli

        5. Inflammatory Bowel Disease
   a. comparison of Crohn's Disease (regional ileitis) to Ulcerative
                 Colitis

H. Pancreatitis   
1. can be acute or chronic
2. acute pancreatitis- 80 -90% recover without difficulty, mortality =
    10%
3. causes
       alcoholism (most common in U.S.)
        billiard tract Dx
        post op abdominal surgery
        blunt abdominal trauma
        metabolic (increased serum calcium)
                infections
                connective tissue disease, intestinal diseases
                drugs

        4. autodigestion is triggered (trypsinogen activated to trypsin in
         pancreas inappropriately)- leads to inflammation, release of
         bradykinins, histamine. Get edema, intestinal hemorrhage, vascular
         damage, fat necrosis (Ca+  is chelated to fats, thus taken out of
         circulation causing a hypocalcemia)    

        5. Major signs and symptoms
            a. pain (intensified by eating)
            b. low grade fever
            c. hypovolemia    

        6. serum amylase rises, begins to decrease by third day

Discussion  

    Digestion depends on three functions: movement, secretion and absorption. All three functions need to be coordinated. To do this, the gastrointestinal tract is highly innervated with nerves. Sometimes, the gut of the digestive tract is referred to as the body's "second brain". Serotonin is a major neurotransmitter of the GI tract, so it is no surprise that a medication such as Prozac (which is a serotonin uptake inhibitor) has so many side effects related to the GI system.
    H. pylori is a spirochete implicated in the formation of gastric and duodenal ulcers, also gastritis and stomach cancer. H. pylori colonizes the mucous layer lining the antrum of the stomach, yet it can somehow also cause duodenal ulcers?  It is transmitted via the fecal oral route. Many infected individuals never have symptoms. It is somewhat of a mystery why some people with H. pylori develop complications and others don't. There may be co-factors, like genetic tendencies and smoking which are contributory. For example, people with O type blood ( a genetic factor) have been found to have a higher number of receptor sites for H. pylori to bind to.  H. pylori can trigger off an inflammatory reaction as the result of the release of ammonia. The bacteria produces an enzyme, urease, which enables it to produce large amounts of ammonia. The ammonia is protective to H. pylori since it neutralizes the largely acidic environment in which it finds itself and, therefore, enables it to continue colonizing the gastric mucosa.

Clinically  

    Dyspepsia may be present in as much as 25% of the U.S. population. This symptom may be the result of nonulcer dyspepsia (NUD) (common finding in young woman), peptic ulcer disease (PUD) gastroesophageal reflux disease (GERD) chronic pancreatitis and gastric and esophageal malignancies
    Bleeding is a frequent complication of GI disease. Hematemesis is the vomiting of blood. Hematochezia is the passage of bloody stools. When blood is in contact with gastric acid for several hours and then is vomited, it appears as "coffee ground"  emesis . Melena is the passage of dark, "tarry stools" . It is the result of partially digested blood. It is important to keep in mind that ingestion of iron, charcoal, Pepto bismol and licorice can turn the stools black.  An examination of the pattern of blood in the stools can be diagnostic of the location of the bleed in the GI tract. Bright red blood only is due to bleeding in the rectum or lower sigmoid. Maroon blood with diarrhea represents bleeding above the mid transverse colon. Melena with diarrhea is bleeding above the duodenojejunal junction, whereas melena without diarrhea is bleeding above the mid transverse colon. Stool with small amounts of blood may not be visible to the naked eye (occult blood). It can be tested for with a stool guiac test.
    80% of all cases of upper GI bleeding is due to ulcers of duodenum, esophagus and stomach. 10 -20% is due to erosive gastritis and 5% to esophageal varices. Lower GI bleeds are due to anal lesions (fissures, hemorrhoids, fistulas), diseases of the rectum and colon (cancer, ulcerative colitis, rectal polyps) and diverticuli (most often found in sigmoid colon).