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Gastrointestinal 1

  1. Anatomy & Physiology (illustration)
  2. Upper gastrointestinal tract
    1. Mouth: teeth and salivary glands
    2. Esophagus
    3. Stomach (illustration)
  3. Lower gastrointestinal tract
    1. Small intestine - digests and absorbs, mixes via peristalsis, receives secretions from liver, gallbladder and pancreas
      1. duodenum - joins pylorus of the stomach, is about ten inches long
      2. jejunum - middle section, is about eight feet long
      3. illeum - lower section, is about 12 feet long
    2. Colon- approximately six feet long, absorbs water and sodium (illustration)
      1. ascending
      2. transverse
      3. descending
      4. sigmoid
      5. rectum - last seven - eight inches of intestines
  4. Accessory digestive organs
    1. Liver - largest gland of the body (illustration)
      1. lobes dived into lobules by blood vessels and fibrous material
      2. ducts - hepatic duct from liver; cystic duct from gallbladder; common bile duct formed by hepatic duct and cystic duct and drains into duodenum
      3. functions: Metabolism of fat, carbohydrates and protein
        1. converts glucose to glycogen for storage
        2. converts glycogen to glucose and releases into blood
        3. forms glucose from fats or proteins
        4. breaks down fatty acids into ketones
        5. stores fat
        6. synthesizes triglycerides, phospholipids, cholesterol, and choline (B complex factor)
        7. synthesizes various proteins
        8. converts amino acid to ammonia
        9. converts ammonia to urea
      4. other functions
        1. secretes bile, which is important in the emulsifying of fats
        2. detoxifies substances such as drugs, hormones
        3. metabolizes vitamins
    1. Pancreas (illustration)
      1. fish-shaped organ extending from duodenal curve to the spleen
      2. both an endocrine and exocrine gland
        1. pancreatic cells - empty into duodenum at the hepatopancreatic papilla; secrete enzymes which digest fats, carbohydrates and proteins
        2. islet of Langerhans
          • alpha cells secrete glucagon to promote liver glycogenolysis and gluconeogenesis which ultimately increases blood glucose level
          • beta cells secrete insulin
    2. Gallbladder (illustration)
      1. similar size and shape as a pear
      2. made up of smooth muscle and lined with rugae-arranged mucosa
      3. only purpose is to store bile
      4. empties bile into duodenum when fat is present there
  5. Process of digestion
    1. Purpose - converts foods into a form which can be absorbed and used by the body
    2. Digestive enzymes 
    3. Basic processes
      1. absorption - accomplished by active transport via intestinal cells. Water and solutes move through the intestinal mucosa in opposite direction expected in osmosis and diffusion
      2. metabolism - consists of the sum of all physical and chemical changes that take place within an organism
      3. catabolism - series of chemical reactions that take place within the cell; breaks down food molecules to produce energy
        1. anabolism - synthesis of compounds from simpler compounds
  6. Disorders of Stomach and Colon
  7. Pernicious anemia - anemia caused when tissues fail to absorb enough vitamin B12
    1. Definition/etiology/risk
      1. mucosaand parietalcells of stomach atrophy; stomach fails to produce intrinsic factor, thus cannot properly absorb vitamin B12
      2. possibly an autoimmune disease
      3. may follow gastric resection
    2. Pathophysiology
      1. large RBCs - macrocytic normochromic
      2. hydrochloric acid
    3. Findings
      1. anemia- findings depend on severity
      2. tissue hypoxiaproducing fatigue, weakness, dyspnea, pallor, palpitations
      3. GI symptoms: sore tongue, anorexia, nausea, vomiting, abdominal pain, neurological symptoms
      4. neurological symptoms: paresthesiain hands and feet, weakness, impaired coordination, changes in LOC.
    4. Complications: GI symptoms are reversible, but neurological changes are not
    1. Diagnostics
      1. CBC
      2. bone-marrow biopsy
      3. lack of free hydrochloric acid in stomach
      4. Schilling test
    2. Management
      1. lifelong vitamin B12 therapy
      2. adequate nutrition
      3. blood transfusions as needed
    3. Nursing interventions
      1. monitor for impaired gas exchange
      2. manage fatigue
      3. risk of injury from depressed LOC and impaired coordination
      4. knowledge deficit- need to understand chronic illness
  8. Peptic ulcer diseases - include disorders that ulcerate any part of stomach or intestines.
    1. Gastric ulcers
      1. definition/etiology
        1. incidence higher in the middle-aged and elderly; most common in men ages 45-55
        2. risk factors: aspirin, NSAIDs, steroids, caffeine, and alcohol intake; stress
        3. pathogen: H. pylori
      2. pathophysiology
        1. something disrupts mucosal layer and acid diffuses back into mucosa
        2. commonest site: junction of fundusand pylorus
        3. normal gastric acid secretion
      3. findings
        1. pain, burning or gas, worse with food
        2. pain in left upper epigastric area
        3. nausea/vomiting
        4. bleeding; hematemesis
    1. Duodenal ulcers
      1. etiology/risk factors
        1. excess production of hydrochloric acid
        2. more rapid gastric emptying
        3. familial tendency
        4. stress
        5. more frequent in people with type O blood
        6. more common in men ages 25 to 50
      2. pathophysiology
        1. located 0.5 to 2 cm below pylorus
        2. arteriosclerotic changes in adjacent blood vessels
        3. vagus nerve stimulation causes tissues to release gastrin, which increases secretion of hydrochloric acid
      3. findings
        1. pain, heartburn occur during night or when stomach is empty
        2. pain relieved by food intake
        3. melena (tarry stool; black with digested blood)
      4. diagnostic studies
        1. endoscopy - esophagogastroduodenoscopy
        2. complete blood count (CBC)
        3. test stool for occult blood
      1. complications
        1. hemorrhage
          • treat with tap water lavageto control bleeding
          • administer Intra-arterial vasopressin
          • administer Intravenous fluids and blood replacement
        2. perforationand peritonitis
          • finding: severe abdominal pain
          • finding: board-like abdomen
        3. paralytic ileus (obstruction): scarring may obstruct pylorus