Digestive System Disorders

Chapter 17: Digestive System Disorders

Structures and Their Functions

  • Upper Gastrointestinal Tract
  • Liver
  • Pancreas
  • Lower Gastrointestinal Tract

Functions

  • Processes ingested food and fluids.
  • Breaks them down into their units, controlled by enzymes.
  • Absorbs necessary components via membrane transport mechanisms, mostly in the small intestine.

Anatomy of the Digestive System

  • Mouth: Chews food, saliva adds water and digests carbohydrates.
  • Esophagus: Swallows.
  • Stomach: Mixes and dilutes chyme; gastric secretions digest protein, add intrinsic factor, and are acidic.
  • Small Intestine: Bile emulsifies fat, pancreatic secretions and intestinal secretions digest fat, protein, and carbohydrates, and absorption of nutrients occurs.
  • Colon: Absorbs water and electrolytes.
  • Rectum: Stores until defecation.

Structures of the Gut Wall

  • Mucosa:
    • Epithelium, including mucus-producing cells.
  • Submucosa:
    • Connective tissue, including blood vessels, nerves, lymphatics, and secretory glands.
  • Circular Smooth Muscle Layer
  • Longitudinal Smooth Muscle Layer
  • Serosa:
    • Visceral peritoneum.

Upper Gastrointestinal Tract

  • Oral Cavity
  • Esophagus
  • Stomach

Oral Cavity

  • Initial phase of mechanical breakdown of food (mastication by teeth).
  • Initial chemical digestion using salivary amylase to start carbohydrate breakdown.
  • Formation of bolus.
  • Pharynx
    • Swallowing (deglutition).

Esophagus

  • Closed except during swallowing; skeletal muscle at the superior end, followed by smooth muscle.
  • Swallowing Process:
    • The soft palate is pulled upward.
    • The vocal cords are approximated.
    • The epiglottis covers the larynx.
    • Respiration ceases.
    • The bolus is seized by the constricted pharynx.
    • Bolus of food moves into the esophagus.

Stomach

  • Expansible muscular sac that acts as a reservoir for food and fluid.
  • Three smooth muscle layers facilitate constant mixing and churning of food.
  • Initial digestion of proteins
    • By pepsin, formed by the combination of pepsinogen and HCl (hydrochloric acid).
  • Production of intrinsic factor
    • Essential for the absorption of vitamin B12 in the ileum.
  • Formation of Chyme
  • Absorption of small and lipid-soluble molecules.

Liver

  • "Metabolic factory" of the body.
  • Receives blood from the hepatic portal vein, transporting nutrients from the intestine to the liver.
  • Hepatocytes store nutrients.
    • Play a role in carbohydrate, protein, and fat metabolism.
  • Production of plasma proteins and clotting factors.
  • Breakdown of old and damaged erythrocytes.
  • Bile production.

Pancreas

  • Exocrine pancreas arranged in lobules.
  • Secretes digestive enzymes and electrolytes:
    • Trypsin
    • Chymotrypsin
    • Carboxypeptidase
    • Ribonuclease
    • Pancreatic amylase
    • Bicarbonate ions
  • The pancreatic duct joins the bile duct to enter the duodenum.

Lower Gastrointestinal Tract

  • Small Intestine
    • Duodenum, jejunum, ileum
    • Villi (folds of the mucosa) and microvilli (folds of cell membranes) increase surface area for absorption.
    • Major site for absorption of nutrients.
    • Lacteal: lymphatic vessel.
    • Peyer Patches: lymphatic tissue.
    • Site of production of mucus, enterokinase, peptidases, nucleosidases, lipase, sucrase, maltase, lactase, cholecystokinin (hormone).
  • Large Intestine
    • Resident normal flora.
      • Breakdown of certain food materials.
      • Vitamin K synthesis by bacteria.
    • Fluid and electrolyte reabsorption.
    • Formation of solid feces
    • Mass movements

Major Digestive Enzymes and Their Actions (Table 17-1)

  • Salivary Amylase
    • Source: Parotid gland
    • Action: Splits starch and glycogen into disaccharides
  • Pepsin
    • Source: Gastric chief cells
    • Action: Initiates splitting of proteins
  • Pancreatic Amylase
    • Source: Pancreas
    • Action: Splits starch and glycogen into disaccharides
  • Pancreatic Lipase
    • Source: Pancreas
    • Action: Splits triglycerides into fatty acids and monoglycerides
  • Trypsin, Chymotrypsin, Carboxypeptidase
    • Source: Pancreas
    • Action: Splits proteins into peptides
  • Pancreatic Nucleases
    • Source: Pancreas
    • Action: Splits nucleic acids into nucleotides
  • Intestinal Peptidase
    • Source: Intestinal mucosa
    • Action: Converts peptides into amino acids
  • Intestinal Lipase
    • Source: Intestinal mucosa
    • Action: Converts fats into fatty acids and glycerol
  • Intestinal Sucrase, Maltase, Lactase
    • Source: Intestinal mucosa
    • Action: Converts disaccharides into monosaccharides

Neural and Hormonal Controls

  • Parasympathetic Nervous System (PNS)
    • Primarily through the vagus nerve (cranial nerve [CN] X)
      • Increased motility
      • Increased secretions
  • Sympathetic Nervous System (SNS)
    • Stimulated by factors such as fear and anger
      • Inhibits gastrointestinal activity
      • Causes vasoconstriction
      • Reduced secretions and regeneration of epithelial cells
  • Facial (CN VII) and glossopharyngeal (CN IX) nerves maintain a continuous flow of saliva in the mouth.
  • Distention and stretching of the stomach activate the PNS, increasing peristalsis and gastric secretions.
  • The stomach empties within 2 to 6 hours after a meal.
  • Food in the intestine stimulates intestinal activity through the enterogastric reflex, inhibiting gastric emptying.

Major Controls in the Digestive Tract and Their Effects (Table 17-2)

  • Gastrin
    • Source: Gastric cells
    • Stimulus: Food in the stomach; protein, caffeine, or high pH promotes gastric emptying of chyme
    • Effects: Increases gastric secretions and motility
  • Cholecystokinin
    • Source: Intestinal mucosal cells
    • Stimulus: Protein and fat in the duodenum
    • Effects: Inhibits gastric secretions and motility; stimulates pancreatic enzyme secretion; stimulates gallbladder contractions and release of bile
  • Secretin
    • Source: Intestinal mucosal cells
    • Stimulus: Acidic chyme in the duodenum
    • Effects: Stimulates bile and pancreatic secretions with high bicarbonate content
  • Parasympathetic Nervous System
    • Source: Vagus nerve
    • Stimulus: Taste of food
    • Effects: Increases secretions and peristalsis
  • Sympathetic Nervous System
    • Source: SNS
    • Stimulus: Stress
    • Effects: Decreases secretions and peristalsis; stimulates vasoconstriction in the mucosa

Hormonal Controls

  • Gastrin
    • Secreted by mucosal cells (stomach) in response to distention of the stomach or partially digested substances.
    • Increases gastric motility, relaxes pyloric and ileocecal sphincters, and promotes stomach emptying.
  • Histamine
    • Increased secretion of hydrochloric acid.
  • Secretin
    • Decreases gastric secretions.
  • Cholecystokinin
    • Inhibits gastric emptying and stimulates contraction of the gallbladder.

Digestion and Absorption

  • Carbohydrates
    • Digestion starts in the mouth, followed by digestion in the small intestine.
  • Proteins
    • Digestion starts in the stomach and continues in the small intestine.
  • Lipids
    • Emulsified by bile prior to chemical breakdown.
    • Action of enzymes forms monoglycerides and free fatty acids.
    • Formation of chylomicrons.
  • Fat-Soluble Vitamins
    • Vitamins A, D, E, and K are absorbed with fats.
  • Water-Soluble Vitamins
    • Vitamins B and C diffuse into the blood.
  • Electrolytes
    • Absorbed by active transport or diffusion.
  • Drugs
    • Primarily absorbed in the intestine via various transport mechanisms.
    • Some drugs (e.g., aspirin) are absorbed in the stomach.
  • Water
    • Absorbed primarily by osmosis.
    • About 700 mL of water is secreted into the digestive tract each day.
    • About 2300 mL is ingested in food and fluids.
    • Only 50 to 200 mL leaves the body in feces.
    • Severe vomiting or diarrhea will interrupt this recycling mechanism, affecting the fluid and electrolyte balance of the body.

Common Manifestations of Digestive System Disorders

  • Anorexia, Nausea, Vomiting, and Bulimia
  • Diarrhea
  • Constipation
  • Fluid and Electrolyte Imbalances
  • Pain
  • Malnutrition

Anorexia, Nausea, Vomiting, and Bulimia

  • May be signs of a digestive disorder or other condition elsewhere in the body, such as systemic infection, uremia, emotional responses, motion sickness, pressure in the brain, overindulgence of food or drugs, and pain.
  • Anorexia and vomiting can cause serious complications, including dehydration, acidosis, and malnutrition.
  • Anorexia often precedes nausea and vomiting.
  • Nausea is an unpleasant subjective feeling stimulated by distention, irritation, and inflammation of the digestive tract, as well as smells, visual images, pain, and chemical toxins or drugs.
  • Vomiting (emesis):
    • The vomiting center is located in the medulla and coordinates activities involved in vomiting, protecting the airway during vomiting.
    • Forceful expulsion of chyme from the stomach, sometimes including bile from the intestine.
  • Bulimia:
    • Eating disorder causing damage to structures of the GI tract caused by recurrent vomiting, including oral mucosa, teeth, and esophagus.

Vomiting Center Activation

  • Distention or irritation in the digestive tract.
  • Stimuli from various parts of the brain in response to unpleasant sights or smells, or ischemia.
  • Pain or stress.
  • Vestibular apparatus of the inner ear (motion).
  • Increased intracranial pressure, leading to sudden projectile vomiting without previous nausea.
  • Stimulation of the chemoreceptor trigger zone by drugs, toxins, and chemicals.

Vomiting Reflex Activities

  • Deep inspiration.
  • Closing the glottis, raising the soft palate.
  • Ceasing respiration minimizes the risk of aspiration of vomitus into the lungs.
  • Relaxing the gastroesophageal sphincter.
  • Contracting the abdominal muscles forces gastric contents upward.
  • Reversing peristaltic waves promotes the expulsion of stomach contents.

Characteristics of Vomitus

  • Presence of blood
    • Hematemesis
      • Coffee ground vomitus: brown granular material indicates the action of HCl on hemoglobin.
      • Hemorrhage: red blood may be in vomitus.
  • Yellow- or green-stained vomitus
    • Bile from the duodenum.
  • Deeper brown color
    • May indicate content from the lower intestine.
  • Recurrent vomiting of undigested food
    • Problem with gastric emptying or infection.

Diarrhea

  • Excessive frequency of stools, usually of loose or watery consistency.
  • May be acute or chronic.
  • Frequently with nausea and vomiting when infection or inflammation develops.
  • May be accompanied by cramping pain.
  • Prolonged diarrhea may lead to dehydration, electrolyte imbalance, acidosis, and malnutrition.

Types of Diarrhea

  • Large-Volume Diarrhea (Secretory or Osmotic)
    • Watery stool resulting from increased secretions into the intestine from the plasma.
    • Often related to infection.
    • Limited reabsorption because of the reversal of normal carriers for sodium and/or glucose.
  • Small-Volume Diarrhea
    • Often caused by inflammatory bowel disease.
    • Stool may contain blood, mucus, and pus.
    • May be accompanied by abdominal cramps and tenesmus.
  • Steatorrhea
    • "Fatty diarrhea"
      • Frequent bulky, greasy, loose stools.
      • Foul odor.
      • Characteristic of malabsorption syndromes, such as celiac disease and cystic fibrosis.
      • Fat is usually the first dietary component affected.
      • Its presence interferes with the digestion of other nutrients.
      • The abdomen is often distended.

Blood in Stool

  • Blood may occur in normal stools with diarrhea, constipation, tumors, or an inflammatory condition.
    • Frank Blood
      • Red blood, usually from lesions in the rectum or anal canal.
    • Occult Blood
      • Small hidden amounts, detectable with a stool test.
      • May be caused by small bleeding ulcers.
    • Melena
      • Dark-colored, tarry stool.
      • May result from significant bleeding in the upper digestive tract.

Gas

  • From swallowed air, bacterial action on food, foods, or alterations in motility.
  • Excessive gas causes:
    • Eructation (belching)
    • Borborygmus (stomach rumbling)
    • Abdominal distention and pain
    • Flatus (farting)

Constipation

  • Less frequent bowel movements than normal, resulting in small, hard stools.
  • May be an acute or chronic problem.
  • May be caused by decreased peristalsis, which increases the time for reabsorption of fluid.
  • Periods of constipation may alternate with periods of diarrhea.
  • Chronic constipation may cause hemorrhoids, anal fissures, or diverticulitis.

Causes of Constipation

  • Weakness of smooth muscle because of age or illness.
  • Inadequate dietary fiber or fluid intake.
  • Failure to respond to the defecation reflex or immobility.
  • Neurological disorders.
  • Drugs (i.e., opiates), some antacids, and iron medications.
  • Obstructions caused by tumors or strictures.

Fluid and Electrolyte Imbalances

  • Dehydration and hypovolemia are common complications of digestive tract disorders.
  • Electrolytes are lost in vomiting and diarrhea.
  • Acid-base imbalances:
    • Metabolic Alkalosis
      • Results from the loss of hydrochloric acid with vomiting.
    • Metabolic Acidosis
      • Severe vomiting causes a change to metabolic acidosis because of the loss of bicarbonate of duodenal secretions.
      • Diarrhea causes a loss of bicarbonate.

Pain

  • Visceral Pain
    • Burning sensation: inflammation and ulceration in the upper digestive tract.
    • Dull, aching pain: typical result of the stretching of the liver capsule.
    • Cramping or diffuse pain: inflammation, distention, and stretching of the intestines.
    • Colicky, often severe pain: recurrent smooth muscle spasms or contraction in response to severe inflammation or obstruction.
  • Somatic Pain
    • Somatic pain receptors directly linked to spinal nerves may cause reflex spasm of overlying abdominal muscles.
    • Steady, intense, and often well-localized abdominal pain indicates involvement or inflammation of the parietal peritoneum.
    • Rebound tenderness is identified over the area of inflammation when pressure is released.
  • Referred Pain
    • When visceral and somatic nerves converge at one spinal cord level, the source of visceral pain is perceived as the same as that of the somatic nerve.
    • May assist or delay diagnosis depending on the problem.

Malnutrition

  • May be limited to a specific nutrient or general.
  • Causes of limited malnutrition (specific problem):
    • Vitamin B12 deficiency or iron deficiency.
  • Causes of generalized malnutrition:
    • Chronic anorexia, vomiting, or diarrhea; other systemic causes such as chronic inflammatory bowel disorders or cancer treatments; wasting syndrome; or lack of available nutrients.

Basic Diagnostic Tests

  • Radiography
    • Contrast medium may be used.
  • Ultrasound
    • May show unusual masses.
  • Computed Tomography (CT)
  • Magnetic Resonance Imaging (MRI)
    • CT and MRI may use radioactive tracers and can be used for liver and pancreatic abnormalities.
  • Fiberoptic Endoscopy
    • Used in the upper GI tract.
    • Biopsy may be done during procedures.
  • Sigmoidoscopy and Colonoscopy
    • Biopsy and removal of polyps may be done.
  • Laboratory Analysis of Stool Specimens
    • Check for infection, parasites and ova, bleeding, tumors, and malabsorption.
  • Blood Tests
    • Liver function, pancreatic function, and cancer markers.

Common Therapies and Prevention

  • Dietary Modifications
    • Example—gluten-free diet (celiac disease).
    • Reduced intake of alcohol and coffee.
    • Increased fiber and fluid intake.
  • Stress Reduction Techniques
    • Stress impairs immune function and tissue healing.
  • Drugs
    • A variety of medications are available.

Drugs Used in Digestive System Disorders

  • Antacids
    • To relieve pyrosis (heartburn).
  • Antiemetics
    • To relieve vomiting.
  • Laxatives or Enemas
    • Treatment of acute constipation.
  • Antidiarrheals
    • Reduction of peristalsis to relieve cramps.
  • Sulfasalazine
    • Anti-inflammatory and antibacterial used for acute episodes of inflammatory bowel disease.
  • Clarithromycin or Azithromycin
    • Effective against Helicobacter pylori infection, usually combined with a proton pump inhibitor.
  • Sucralfate
    • Coating agent to enhance the gastric mucosal barrier against irritants such as NSAIDs (nonsteroidal anti-inflammatory drugs).
  • Anticholinergic Drugs
    • Reduce PNS activity to reduce secretions and motility.
  • Histamine 2 Antagonists
    • Useful for gastric reflux.
  • Proton Pump Inhibitors
    • Reduce gastric secretion.

Examples of Drugs Used in Digestive System Disorders (Table 17-3)

  • Antiemetic
    • Dimenhydrinate (Dramamine):
      • Reduces vomiting resulting from drugs, motion sickness, and radiation treatment
    • Prochlorperazine (Stemetil):
      • Reduces vomiting resulting from drugs, motion sickness, and radiation treatment
  • Antidiarrheal
    • Loperamide (Imodium):
      • Reduces intestinal motility
    • Codeine, paregoric
      • Reduces intestinal motility
  • Anti-inflammatory
    • Prednisone (Deltasone - a glucocorticoid):
      • Reduces inflammation
      • Prednisone blocks the immune response
    • Sulfasalazine (Azulfidine):
      • Reduces inflammation
      • Sulfasalazine has antibacterial action
  • Acid-reduction
    • Ranitidine (Zantac):
      • Reduces secretion of hydrochloric acid in the stomach
      • Blocks H2 receptors
    • Lansoprazole (Prevacid)
      • Reduces secretion of hydrochloric acid in the stomach
      • Proton (H+H^+) pump inhibitor
  • Antimicrobial
    • Clarithromycin (Biaxin)
      • Combination therapy for Helicobacter pylori infection
    • Metronidazole (Flagyl)
      • Combination therapy for Helicobacter pylori infection
    • Tetracycline
      • Drugs as indicated by culture and sensitivity
    • Cefoperazone
      • Drugs as indicated by culture and sensitivity
    • Amoxicillin
      • Drugs as indicated by culture and sensitivity
  • Coating Agent
    • Sucralfate (Carafate):
      • Covers ulcer to allow healing
  • Antacid
    • Aluminum-magnesium combinations (Maalox):
      • Reduces hyperacidity
  • Laxative
    • Psyllium (Metamucil) (bulk) or docusate sodium (Colace) (stool softener):
      • Increases fecal bulk and intestinal motility with water
  • Anticholinergics
    • pirenzepine, propantheline bromide
      • Reduces PNS activities - reduced secretions and mobility
  • Histamine-2 blockers
    • Tagamet, Zantac
      • Inhibits acid production in the stomach
  • Proton Pump Inhibitors
    • Prevacid, Prilosec
      • Reduce gastric secretions

Upper Gastrointestinal Tract Disorders

  • Disorders of the Oral Cavity
  • Dysphagia
  • Esophageal Cancer
  • Hiatal Hernia
  • Gastroesophageal Reflux Disease
  • Gastritis
  • Peptic Ulcer
  • Gastric Cancer
  • Dumping Syndrome
  • Pyloric Stenosis

Disorders of the Oral Cavity

  • Congenital Abnormalities
    • Cleft lip and cleft palate
      • Arise in the sixth to seventh week of gestation, most likely of multifactorial origin.
      • Feeding problems of the infant increase the risk of aspirating fluid into respiratory passages.
      • Speech development is impaired, requiring surgical repair as soon as possible, along with therapy with a speech-language pathologist and orthodontist.
  • Inflammatory Lesions
    • Aphthous ulcers
      • Streptococcus sanguis may be involved as part of the oral resident flora.
        • Small painful lesions on movable mucosa, buccal mucosa, floor of the mouth, soft palate, and lateral borders of the tongue usually heal spontaneously.

Disorders of the Oral Cavity: Infections

  • Candidiasis
    • Candida albicans is the causative agent and often part of the resident flora, acting as an opportunistic organism.
    • Oral candidiasis (thrush) is commonly seen in people receiving broad-spectrum antibiotics, during and after cancer therapy, or in immunocompromised individuals or those with diabetes.
      • May appear as red, swollen areas or as irregular patches of a white curd-like material.
  • Herpes Simplex Type 1 Infection
    • Herpes simplex virus type 1 (HSV-1) is transmitted by kissing or close contact.
      • The virus remains dormant in the sensory ganglion and is activated by stress, trauma, or other infection.
      • This leads to the formation of blisters, ulcers, and clear fluid release, containing the virus, which can be autoinoculated to other areas.
      • Lesions heal spontaneously in 7 to 10 days, and the acute stage may be alleviated by antiviral medication.
      • May spread to eyes, causing conjunctivitis and keratitis.
  • Syphilis
    • Caused by Treponema pallidum.
      • May cause oral lesions and is highly contagious during the first and second stages.
      • Primary Stage
        • Chancre, a painless ulcer on the tongue, lip, or palate, heals spontaneously in 1 or 2 weeks.
      • Secondary Stage
        • Red macules or papules on the palate are highly infectious and heal spontaneously.
      • Both stages are treated with long-acting penicillin.

Disorders of the Oral Cavity: Dental Problems

  • Caries
    • Streptococcus mutans is the initiating microbe, followed by Lactobacillus in large numbers.
      • These bacteria break down sugars and produce large quantities of lactic acid, which dissolves the mineral in tooth enamel, leading to tooth erosion and caries formation.
      • Caries is promoted by the frequent intake of sugars and acids.
      • Fluoride is used as an anticaries treatment.
  • Gingivitis
    • Changes in the gingivae may be a local or systemic problem, causing inflammation of the gingiva.
      • Tissue becomes red, soft, swollen, and bleeds easily, possibly as a result of accumulated plaque or inadequate oral hygiene.
      • Toothbrush trauma from improper or excessive brushing creates extensive grooving on the tooth surface and increases plaque retention and damage to the gingivae.
  • Periodontal Disease
    • Infection and damage to the periodontal ligament and bone, with a predisposing condition of gingivitis.
      • Caused by microorganisms as a result of poor dental hygiene, leading to the possible subsequent loss of teeth.
      • Several categories, depending on the degree of the disease, which may be aggravated by systemic disease and medications that reduce salivary secretions.
    • Periodontitis occurs when organisms enter the gingival blood vessels and travel to the connective tissues and bone of the dental arch.
      • Resorption of bone and loss of ligament fibers result in a weakened attachment of teeth, potentially resulting in total loss of the tooth from the socket.
      • Treated by antimicrobials, local surgery of the gingiva, and improved dental hygiene.
  • Hyperkeratosis
    • Leukoplakia (example)
      • Whitish plaque or epidermal thickening of mucosa occurs on the buccal mucosa, palate, or lower lip and may be related to smoking or chronic irritation.
      • Lesions require monitoring as epithelial dysplasia beneath the plaque may develop into squamous cell carcinoma.

Cancer of the Oral Cavity

  • Squamous cell carcinoma is the common type and often develops in persons older than 40 years, particularly smokers with preexisting leukoplakia or alcohol abuse.
    • It is commonly found on the floor of the mouth and lateral borders of the tongue, with multiple lesions possible.
  • Kaposi sarcoma is seen in patients with AIDS.
  • Lip cancer has a better prognosis, common in smokers, particularly pipe smokers.

Salivary Gland Disorders

  • Sialadenitis
    • Inflammation of the salivary glands may be infectious or noninfectious.
    • The most commonly affected is the parotid gland.
  • Mumps
    • Infectious parotitis is a viral infection for which a vaccine is available.
  • Noninfectious Parotitis
    • Often seen in older adults who lack adequate fluid intake and mouth care.
  • The most malignant tumor of the salivary glands is mucoepidermoid carcinoma.

Dysphagia

  • Difficulty swallowing, caused by neurological deficits, muscular disorders, or mechanical obstruction.

    • Results in pain with swallowing, the inability to swallow larger pieces of solid material, or difficulty swallowing liquids.

  • Neurological Deficit

    • Can be caused by infection, stroke, brain damage, or achalasia.
    • Achalasia is a failure of the lower esophageal sphincter to relax because of a lack of innervation.

  • Muscular Disorder

    • Impairment from muscular dystrophy.

  • Mechanical Obstruction

    • Congenital atresia is a developmental anomaly where upper and lower esophageal segments are separated.
    • Stenosis is a narrowing of the esophagus that may be developmental or acquired, secondary to fibrosis, chronic inflammation, ulceration, or radiation therapy.
    • Esophageal diverticula are outpouchings of the esophageal wall that are congenital or acquired following inflammation, causing irritation, inflammation, and scar tissue.
      • Signs include dysphagia, foul breath, chronic cough, and hoarseness.
    • Tumors may be internal or external.

Esophageal Cancer

  • Primarily squamous cell carcinoma, usually in the distal esophagus.
  • Significant dysphagia occurs in later stages, leading to a poor prognosis because of late manifestations.
  • Associated with chronic irritation due to chronic esophagitis, achalasia, hiatal hernia, alcohol abuse, or smoking.

Hiatal Hernia

  • Part of the stomach protrudes into the thoracic cavity.
  • Sliding Hernia
    • The more common type, where portions of the stomach and gastroesophageal junction slide up above the diaphragm.
  • Rolling or Paraesophageal Hernia
    • Part of the fundus of the stomach moves up through an enlarged or weak hiatus in the diaphragm and may become trapped.
  • Food may lodge in the pouch of the hernia, causing inflammation of the mucosa and reflux of food up the esophagus, potentially causing chronic esophagitis.
  • Signs include heartburn or pyrosis, frequent belching, increased discomfort when laying down, and substernal pain that may radiate to the shoulder and jaw.

Gastroesophageal Reflux Disease

  • Periodic reflux of gastric contents into the distal esophagus causes erosion and inflammation.
  • Often seen in conjunction with a hiatal hernia.
  • Severity depends on the competence of the lower esophageal sphincter, and delayed gastric emptying may be a factor.
  • Avoidance is recommended of caffeine, fatty and spicy foods, alcohol, smoking, and certain drugs.
  • Medication may reduce reflux and inflammation.

Gastritis: Acute Gastritis

  • Gastric mucosa is inflamed and may be ulcerated and bleeding.
  • May result from infection by microorganisms, allergies to foods, spicy or irritating foods, excessive alcohol intake, ingestion of aspirin or other NSAIDs, ingestion of corrosive or toxic substances, or radiation or chemotherapy.
  • Basic signs of gastrointestinal irritation include anorexia, nausea, and vomiting, which may develop.
    • Hematemesis is caused by bleeding, along with epigastric pain, cramps, or general discomfort.
    • With infection, diarrhea may develop.
  • Acute gastritis is usually self-limiting, with complete regeneration of gastric mucosa.
    • Supportive treatment is provided for prolonged vomiting and may require treatment with antimicrobial drugs.

Gastritis: Chronic Gastritis

  • Characterized by atrophy of the stomach mucosa, loss of secretory glands, and reduced production of intrinsic factor.
  • Helicobacter pylori infection is often present.
  • Signs may be vague, including mild epigastric discomfort, anorexia, and intolerance for certain foods.
  • An increased risk of peptic ulcers and gastric carcinoma exists.
  • Certain autoimmune disorders are associated with one type of chronic gastric atrophy.

Gastritis: Gastroenteritis

  • Inflammation of the stomach and intestine, usually caused by infection, but may also be caused by allergic reactions to food or drugs.
  • Microbes can be transmitted by fecally contaminated food, soil, and/or water.
    • Most infections are self-limiting, but serious illness may result in compromised hosts or virulent organisms.
    • May cause epidemic outbreaks in refugee or disaster settings, with safe sanitation essential for prevention.

Common Infections Transmitted by Food and Water (Table 17-4)

  • Staphylococcus aureus
    • Source: Food handlers
    • Incubation: 1-7 hr (2-4, average)
    • Pathophysiology: Enterotoxin (exotoxin), heat-stable
    • Manifestations: Sudden severe nausea, vomiting, and cramps; sometimes diarrhea. Subnormal body temperature and low blood pressure
  • Escherichia coli (traveler's diarrhea)
    • Source: Fecal contamination of food and water
    • Incubation: 10-12 hr
    • Pathophysiology: Various strains may release enterotoxins (increase secretions) or invade mucosa
    • Manifestations: Profuse watery diarrhea, sometimes with blood or mucus. Vomiting and abdominal cramps often present
  • Salmonella species
    • Source: Fecal contamination of food or undercooked or raw eggs, poultry, shellfish. Contaminated work surfaces
    • Incubation: 6-72 hr
    • Pathophysiology: Organisms multiply in intestine, causing inflammation and ulceration
    • Manifestations: Sudden diarrhea, abdominal pain, and fever. Sometimes vomiting
  • Rotavirus
    • Source: Oral-fecal (infants)
    • Incubation: 24-72 hr
    • Pathophysiology: Inflammation and loss of villi
    • Manifestations: Vomiting, severe watery diarrhea, fever
  • Norwalk virus
    • Source: Oral-fecal (adults/older children) shellfish, fomites
    • Incubation: 24-48 hr
    • Pathophysiology: Damage villi
    • Manifestations: Vomiting, diarrhea, and cramps, headache, fever
  • Entamoeba histolytica (amebic dysentery)
    • Source: Fecal contamination of water and vegetables
    • Incubation: 2-4 wk
    • Pathophysiology: Protozoan parasite with cyst stage and active trophozoite stage; may invade mucosa, causing abscesses and granulomas
    • Manifestations: Diarrhea with blood and mucus, may alternate with constipation. Fever and chills
  • Listeria sp.
    • Source: Found in soil and water
    • Incubation: 30-70 days
    • Pathophysiology: Infection causes