[1] MSN 2 LEC MIDTERM

• Functions of the gastrointestinal (GI) system


  • Process food substances
  • Absorb the products of digestion into the blood
  • Excrete unabsorbed materials
  • Provide an environment for microorganisms to synthesize nutrients, such as vitamin K
• Mouth


  Contains the lips, cheeks, palate, tongue, teeth, salivary glands, muscles, and maxillary bones
• Saliva


  Contains the enzyme amylase (ptyalin), which aids in digestion
• Esophagus


  • Collapsible muscular tube about 10 inches (25 cm) long
  • Carries food from the pharynx to the stomach
• Stomach


  • Contains the cardia, fundus, body, and pylorus
  • Mucous glands are located in the mucosa and prevent autodigestion by providing an alkaline protective covering
  • The lower esophageal (cardiac) sphincter prevents reflux of gastric contents into the esophagus
  • The pyloric sphincter regulates the rate of stomach emptying into the small intestine
  • Hydrochloric acid kills microorganisms, breaks food into small particles, and provides a chemical environment that facilitates gastric enzyme activation
  • Pepsin is the chief coenzyme of gastric juice, which converts proteins into proteoses and peptones
  • Intrinsic factor comes from parietal cells and is necessary for the absorption of vitamin B12
  • Gastrin controls gastric acidity
• Small intestine


  • The duodenum contains the openings of the bile and pancreatic ducts
  • The jejunum is about 8 feet (2.4 meters) long
  • The ileum is about 12 feet (3.7 meters) long
  • The small intestine terminates in the cecum
• Pancreatic intestinal juice enzymes

  • Amylase digests starch to maltose
  • Maltase reduces maltose to monosaccharide glucose
  • Lactase splits lactose into galactose and glucose
  • Sucrase reduces sucrose to fructose and glucose
  • Nucleases split nucleic acids to nucleotides
  • Enterokinase activates trypsinogen to trypsin
• Large intestine


  • About 5 feet (1.5 meters) long
  • Absorbs water and eliminates wastes
  • Intestinal bacteria play a vital role in the synthesis of some B vitamins and vitamin K
  • Colon: Includes the ascending, transverse, descending, and sigmoid colons and rectum
  • The ileocecal valve prevents contents of the large intestine from entering the ileum
  • The internal and external anal sphincters control the anal canal
• Peritoneum


  Lines the abdominal cavity and forms the mesentery that supports the intestines and blood supply
• Liver


  • The largest gland in the body, weighing 3 to 4 pounds (1.4 to 1.8 kg)
  • Contains Kupffer cells, which remove bacteria in the portal venous blood
  • Removes excess glucose and amino acids from the portal blood
  • Synthesizes glucose, amino acids, and fats
  • Aids in the digestion of fats, carbohydrates, and proteins
  • Stores and filters blood (200 to 400 mL of blood stored)
  • Stores vitamins A, D, and B and iron
  • The liver secretes bile to emulsify fats (500 to 1000 mL of bile/day)
  • Hepatic ducts: Deliver bile to the gallbladder via the cystic duct and to the duodenum via the common bile duct, the common bile duct opens into the duodenum, with the pancreatic duct at the ampulla of Vater, the sphincter prevents the reflux of intestinal contents into the common bile duct and pancreatic duct
• Gallbladder


  • Stores and concentrates bile and contracts to force bile into the duodenum during the digestion of fats
  • The cystic duct joins the hepatic duct to form the common bile duct
  • The sphincter of Oddi is located at the entrance to the duodenum
  • The presence of fatty materials in the duodenum stimulates the liberation of cholecystokinin, which causes contraction of the gallbladder and relaxation of the sphincter of Oddi
• Pancreas


  • Exocrine gland: Secretes sodium bicarbonate to neutralize the acidity of the stomach contents that enter the duodenum, Pancreatic juices contain enzymes for digesting carbohydrates, fats, and proteins
  • Endocrine gland: Secretes glucagon to raise blood glucose levels and secretes somatostatin to exert a hypoglycemic effect, The islets of Langerhans secrete insulin, Insulin is secreted into the bloodstream and is important for carbohydrate metabolism
• Upper GI tract study (barium swallow)

  • Examination of the upper GI tract under fluoroscopy after the client drinks barium sulfate
  • Preprocedure: Withhold foods and fluids for 8 hours prior to the test
  • Postprocedure: A laxative may be prescribed, Instruct the client to increase oral fluid intake to help pass the barium, Monitor stools for the passage of barium (stools will appear chalky white for 24 to 72 hours postprocedure) because barium can cause a bowel obstruction
• Capsule endoscopy


  • A procedure that uses a small wireless camera shaped like a medication capsule that the client swallows; the test will detect bleeding or changes in the lining of the small intestine
  • The camera travels through the entire digestive tract and sends pictures to a small box that the client wears like a belt; the small box saves the pictures, which are then transferred to a computer for viewing once the test is complete
  • Preprocedure: A bowel preparation will be prescribed, The client will need to maintain a clear liquid diet on the evening before the exam; additionally, NPO (nothing by mouth) status is maintained for 3 hours before and after swallowing the capsule (time for NPO status is prescribed by the PHCP but is usually 2 to 3 hours)
• Gastric analysis


  • Gastric analysis requires the passage of a nasogastric (NG) tube into the stomach to aspirate gastric contents for the analysis of acidity (pH), appearance, and volume; the entire gastric contents are aspirated, and then specimens are collected every 15 minutes for 1 hour
  • Medication, such as histamine or pentagastrin, may be administered subcutaneously to stimulate gastric secretions; some medications may produce a flushed feeling
  • Esophageal reflux of gastric acid may be diagnosed by ambulatory pH monitoring; a probe is placed just above the lower esophageal sphincter and connected to an external recording device. It provides a computer analysis and graphic display of results
  • Preprocedure: Fasting for at least 12 hours is required before the test, Use of tobacco and chewing gum is avoided for 24 hours before the test, Medications that stimulate gastric secretions are withheld for 24 to 48 hours
  • Postprocedure: Client may resume normal activities, Refrigerate gastric samples if not tested within 4 hours
• Upper GI endoscopy


  • Also known as esophagogastroduodenoscopy, Following sedation, an endoscope is passed down the esophagus to view the gastric wall, sphincters, and duodenum; tissue specimens can be obtained
  • Preprocedure: The client must be NPO for 6 to 8 hours before the test, A local anesthetic (spray or gargle) is administered along with medication that provides moderate sedation just before the scope is inserted, Medication may be administered to reduce secretions, and medication may be administered to relax smooth muscle, The client is positioned on the left side to facilitate saliva drainage and to provide easy access of the endoscope, Airway patency is monitored during the test, and pulse oximetry is used to monitor oxygen saturation; emergency equipment should be readily available
  • Postprocedure: Monitor vital signs, Client must be NPO until the gag reflex returns (1 to 2 hours), Monitor for signs of perforation (pain, bleeding, unusual difficulty in swallowing, elevated temperature), Maintain bed rest for the sedated client until alert, Lozenges, saline gargles, or oral analgesics can relieve a minor sore throat (not given to the client until the gag reflex returns)
• Fiberoptic colonoscopy


  • Colonoscopy is a fiberoptic endoscopy study in which the lining of the large intestine is visually examined; biopsies and polypectomies can be performed
  • Cardiac and respiratory function is monitored continuously during the test
  • Colonoscopy is performed with the client lying on the left side with the knees drawn up to the chest; position may be changed during the test to facilitate passing of the scope
  • Preprocedure: Adequate cleansing of the colon is necessary, as prescribed by the PHCP, A clear liquid diet is started on the day before the test. Red, orange, and purple (grape) liquids are to be avoided, Consult with the PHCP regarding medications that must be withheld before the test, Client is NPO for 4 to 6 hours prior to the test, Moderate sedation is administered intravenously, Medication may be administered to relax smooth muscle
  • Postprocedure: Monitor vital signs, Provide bed rest until alert, Monitor for signs of bowel perforation and peritonitis, Remind the client that passing flatus, abdominal fullness, and mild cramping are expected for several hours, Instruct the client to report any bleeding to the PHCP
• The client receiving oral liquid bowel cleansing preparations or enemas is at risk for fluid and electrolyte imbalances
• Laparoscopy


  Performed with a fiberoptic laparoscope that allows direct visualization of organs and structures within the abdomen; biopsies may be obtained
• Endoscopic retrograde cholangiopancreatography (ERCP)


  • Examination of the hepatobiliary system is performed via a flexible endoscope inserted into the esophagus to the descending duodenum; multiple positions are required during the procedure to pass the endoscope
  • If medication is administered before the procedure, the client is monitored closely for signs of respiratory and central nervous system depression, hypotension, oversedation, and vomiting
  • Preprocedure: Client is NPO for 6 to 8 hours, Inquire about previous exposure to contrast media and any sensitivities or allergies, Moderate sedation is administered
  • Postprocedure: Monitor vital signs, Monitor for the return of the gag reflex, Monitor for signs of perforation or peritonitis
• Magnetic resonance cholangiopancreatography (MRCP)


  • Uses magnetic resonance to visualize the biliary and pancreatic ducts in a noninvasive way
  • Preprocedure and postprocedure: see ERCP
• Endoscopic ultrasonography


  • Provides images of the GI wall and digestive organs
  • Preprocedure and postprocedure: Care is similar to that implemented for endoscopy
• Following endoscopic procedures, monitor for the return of the gag reflex before giving the client any oral substance. If the gag reflex has not returned, the client could aspirate
• Computed tomography (CT) scan

  • Noninvasive cross-sectional view that can detect tissue densities in the abdomen, including in the liver, spleen, pancreas, and biliary tree
  • Can be performed with or without contrast medium
  • Preprocedure: Client is NPO for at least 4 hours, If contrast medium will be used, assess for previous sensitivities and allergies
  • Postprocedure: No specific care is required
• Paracentesis


  • Description and preprocedure: Ensure that the client understands the procedure and that informed consent has been obtained, Obtain vital signs, including weight, and assist the client to void, Position the client upright, Assist the primary health care provider (PHCP), monitor vital signs, and provide comfort and support during the procedure, Apply a dressing to the site of puncture
  • Postprocedure: Monitor vital signs, Measure fluid collected, describe, and record, Label fluid samples and send to the laboratory for analysis, Apply a dry sterile dressing to the insertion site; monitor the site for bleeding, Measure abdominal girth and weight, Monitor for hypovolemia, electrolyte loss, mental status changes, or encephalopathy, Monitor for hematuria caused by bladder trauma, Instruct the client to notify the PHCP if the urine becomes bloody, pink, or red
• The rapid removal of fluid from the abdominal cavity during paracentesis leads to decreased abdominal pressure, which can cause vasodilation and resultant shock; therefore, heart rate and blood pressure must be monitored closely
• Liver enzyme levels


  Alkaline phosphatase (ALP), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) are elevated with liver damage or bilary obstruction
• Normal reference intervals


  ALP, 38-126 U/L (0.65-2.14 µkat/L); AST, 0 to 35 U/L (0 to 35 U/L); ALT, 4 to 36 U/L (4 to 36 U/L)
• Prothrombin time


  Prolonged with liver damage, normal reference interval: 11 to 12.5 seconds
• Serum ammonia level


  Assesses the ability of the liver to deaminate protein byproducts, normal reference interval: 10 to 80 mcg/dL (6 to 47 mcmol/L)
• Cholesterol level


  Increased indicates pancreatitis or biliary obstruction, normal reference interval: less than 200 mg/dL (less than 5.0 mmol/L)
• Bilirubin level


  Increased indicates liver damage or biliary obstruction, normal reference intervals: total, 0.3 to 1.0 mg/dL (5.1 to 17 mcmol/L); indirect, 0.2 to 0.8 mg/dL (3.4 to 12 mcmol/L); direct, 0.1 to 0.3 mg/dL (1.7 to 5.1 mcmol/L)
• Amylase and lipase levels

  Increased values indicate pancreatitis, normal reference intervals: amylase, 60 to 120 Somogyi units/dL (100 to 300 U/L); lipase, 0 to 160 U/L (0 to 160 U/L)
• Gastroesophageal reflux disease


  The backflow of gastric and duodenal contents into the esophagus, caused by an incompetent lower esophageal sphincter (LES), pyloric stenosis, or motility disorder
• Symptoms of gastroesophageal reflux disease

  • Heartburn
  • Epigastric pain
  • Dyspepsia
  • Nausea, regurgitation
  • Pain and difficulty with swallowing
  • Hypersalivation
• Gastritis


  Inflammation of the stomach or gastric mucosa
• Causes of acute gastritis

  • Ingestion of food contaminated with disease-causing microorganisms
  • Ingestion of irritating or highly seasoned food
  • Overuse of aspirin or other NSAIDs
  • Excessive alcohol intake
  • Bile reflux
  • Radiation therapy
• Causes of chronic gastritis

  • Benign or malignant ulcers
  • Helicobacter pylori infection
  • Autoimmune diseases
  • Dietary factors
  • Medications
  • Alcohol
  • Smoking
  • Reflux
• Peptic ulcer disease


  An ulceration in the mucosal wall of the stomach, pylorus, duodenum, or esophagus in portions accessible to gastric secretions
• Gastric ulcers


  Ulceration of the mucosal lining that extends to the submucosal layer of the stomach