Gastrointestinal System Chapters 56 & 57 PDF

## Intro GI System * **Chapters 56 & 57** * **Drugs Affecting Gastro Secretions** ## Key Terms * **bile:** fluid produced in the liver and stored in the gallbladder, contains cholesterol and bile salts, essential for the proper breakdown, and absorption of fats * **chyme:** contents of the stomac...

## Intro GI System * **Chapters 56 & 57** * **Drugs Affecting Gastro Secretions** ## Key Terms * **bile:** fluid produced in the liver and stored in the gallbladder, contains cholesterol and bile salts, essential for the proper breakdown, and absorption of fats * **chyme:** contents of the stomach containing ingested food, secreted enzymes, water, and mucus * **gallstones:** hard crystals formed in the gallbladder when the bile containing many crystalline substances is concentrated * **gastrin:** substance secreted by the stomach in response to many stimuli, stimulates the release of hydrochloric acid from the parietal cells and pepsin from the chief cells, causes histamine release at histamine-2 receptors to effect the release of acid * **histamine-2 (H2) receptors:** sites near the parietal cells of the stomach that, when stimulated, cause the release of hydrochloric acid into the lumen of the stomach, also found near cardiac cells * **hydrochloric acid:** acid released by the parietal cells of the stomach in response to gastrin release or parasympathetic stimulation, makes the stomach contents more acidic to aid digestion and breakdown of food products * **local gastrointestinal reflex:** reflex response to various stimuli that allows the GI tract local control of its secretions and movements based on the contents or activity of the whole GI system * **nerve plexus:** a network of nerve fibers running through the wall of the GI tract that allows local reflexes and control * **pancreatic enzymes:** digestive enzymes secreted by the exocrine pancreas, including pancreatin and pancrelipase, which are needed for the proper digestion of fats, proteins, and carbohydrates * **peristalsis:** type of GI movement that moves a food bolus forward, characterized by a progressive wave of muscle contraction * **saliva:** fluid produced by the salivary glands in the mouth in response to tactile stimuli and cerebral stimulation, contains enzymes to begin digestion, as well as water and mucus to make the food bolus slippery, and easier, to swallow * **segmentation:** GI movement characterized by contraction of one segment of the small intestine while the next segment is relaxed, the contracted segment then relaxes, and the relaxed segment contracts, exposes the chyme to a vast surface area to increase absorption * **swallowing:** complex reflex response to a bolus in the back of the throat, allows passage of the bolus into the esophagus and movement of ingested contents into the GI tract ## System Overview The GI system begins at the mouth and ends at the anus, a long tube extends between them, and is composed of the esophagus, the stomach, the small intestine, and the large intestine. Essential functions are digestion and absorption of nutrients. The GI tract comprises four layers: the mucosa, the muscularis mucosa, the nerve plexus, and the adventitia. The GI system has four major activities: * Secretion of enzymes, acid, bicarbonate, and mucus * Digestion of food into usable and absorbable components * Absorption of water and almost all of the essential nutrients needed by the body * Motility (movement) of food and secretions through the system (what is not used is excreted in the form of feces) ## Vomiting * Vomiting: complex reflex mediated through the medulla after stimulation of the chemoreceptor trigger zone, protective reflex, to remove possibly toxic substances from the stomach * 2 Centers in the brain can stimulate vomiting: Chemoreceptor Trigger Zone (CTZ) and Vomiting Center (VC) * The cause of vomiting should be identified before treatment unless dehydration is severe and causing an electrolyte imbalance. ## Peptic Ulcer Disease and GERD * Peptic Ulcer disease is different from GERD. The majority of gastric and duodenal ulcers can be attributed to H Pylori infection. * Non-invasive breath testing can confirm H Pylori infection * Evidence-based treatment is triple or quadruple therapy of antibacterials, proton pump inhibitors (PPI's) and bismuth and/or metronidazole for 7-14 days. After triple or quadruple treatment, H2Blocker therapy is recommended for 6 wks. * Ulcers present, as a gnawing/aching pain. Gastric: Pain begins 30 minutes to 1.5 hours after eating. Duodenal: Pain begins 2-3 hours after eating * GERD, also called reflux esophagitis, is chronic and presents as indigestion and a burning sensation above the stomach. * All proton pump inhibitors are approved for GERD treatment. * PPI's relieve symptoms faster, and maintain healing better than H2 Blockers ## Non-Pharmacologic Measures and Teaching Points for GERD & PUD * Avoid tobacco * Avoid alcohol * Weight loss (if obese) * Avoid hot, spicy, and greasy (high fat) foods * Cautious use of NSAIDS and steroids * Avoid eating before bedtime * Wear loose-fitting clothing (GERD only) * Elevate the head of the bed (GERD only) ## Antiulcer Drugs: Antacids * **Treats Ulcers and GERD** * **Mech of action:** Neutralizes HCl acid and reduces pepsin activity (They do NOT coat the ulcer) * **2 types of antacids:** Systemic and Non-systemic **Systemic:** * **Sodium Bicarbonate:** One of the first antiulcer drugs, MANY side effects, RARELY -used to treat peptic ulcers * **Calcium (salts) Carbonate:** Most effective in neutralizing acids, can cause hypercalcemia, milk-alkali syndrome (which is now called Burnett syndrome), and renal calculi **Non-Systemic:** Alkaline Salts * **Aluminum:** Causes constipation, also used to lower serum phosphate levels * In patients with renal insufficiency, aluminum can accumulate in the brain and can cause encephalopathy * Prolonged use of aluminum causes hypophosphatemia and osteoporosis * **SE:** hypercalcemia, anorexia, constipation, weakness * **Magnesium:** Causes diarrhea, is a better neutralizer, contraindicated with impaired renal function due to risk of hypermagnesemia * **SE:** N/V/D, abd pain, hypermagnesemia * **NOTE:** the above antacids contain sodium! ## Antiulcer Drugs: Antacids... Continued * **Milk-alkali syndrome (Burnett Syndrome)** - Nausea, vomiting, confusion, headache * **Combination aluminum and magnesium products** neutralize acids without causing diarrhea or constipation because they counteract their own side effects! * **Nursing Consideration:** May need to monitor electrolytes, urinary pH, calcium, and phosphate levels **Teaching Points:** * Report pain, coughing, or vomiting of blood * Take antacids 1-3 hours after meals and at bedtime (Don't take them at mealtime!) * Avoid taking antacids with milk or foods high in vitamin D * Avoid taking antacids within 2 hours of other medications * **Proper administration:** Chewables: Chew thoroughly, followed by water; Liquid: Follow with 2-4 oz. of water (too much water will increase gastric emptying time) * **Diet:** Avoid alcohol, high-fat and spicy foods, caffeine, chocolate * Stools may appear speckled or white * Stop smoking ## Antiulcer Drugs: H2 Blockers * **Cimetidine (Tagamet), Famotidine (Pepcid), Nizatidine (Axid), and Ranitidine (Zantac)** * **H2 Blockers treat ulcers and GERD** * **Mech of action:** Prevents acid reflux in the esophagus by blocking the H2 receptors of the parietal cells in the stomach which reduces gastric acid secretion and concentration * Cimetidine was the first drug in this class, but has the MOST side effects, and MANY drug-drug interactions. * **SE:** Headache, dizziness, drowsiness, agitation, diarrhea, pruritis, skin rash, gynecomastia, decreased libido, erectile dysfunction **Teaching Points:** * Do not take at the same time as antacids * Drug-induced impotence, and gynecomastia are reversible * Eat foods rich in Vitamin B12 * Avoid smoking, alcohol, caffeine, spicy foods * Take BEFORE meals or at bedtime ## Antiulcer Drugs: Proton Pump Inhibitors * **Lansoprazole (Prevacid), Omeprazole (Prilosec), Pantoprazole (Protonix),, and Esomeprazole (Nexium)** * **Uses:** Treats peptic ulcers, GERD, and Zollinger-Ellis syndrome * **Mech of action:** Suppresses gastric acid secretion by inhibiting the hydrogen/potassium ATPase enzyme system located in the gastric parietal cells * Inhibits gastric acid secretion 90% more than the H2 blockers! * Ulcer relief, usually occurs, within one week! * **SE:** Headache, dizziness, diarrhea, abd pain, rash * **Note:** May increase LFT’s, creatinine, potassium, and urea levels (BUN) * May cause low magnesium levels, low sodium levels, and high triglycerides levels. **Teaching Points:** * Swallow tablets whole, do not crush, chew or split * Take 30-60 minutes BEFORE meals * Teach patient, to recognize signs of low magnesium levels (fatigue, muscle cramps, arrhythmias, dizziness, nausea, vomiting, numbness/tingling, anxiety, insomnia) ## Gastrointestinal Protectant: Sucralfate (Carafate) * **Mech of action:** Combines with protein to form a viscous substance that covers the ulcer and protects it from acid and pepsin * Usually given four times a day, before meals, and at bedtime * NOT systemically absorbed, so there are VERY FEW side effects, but it can cause constipation, and flatulence * **Therapy usually requires 4-8 weeks for optimal ulcer healing** **Teaching Points:** * Avoid smoking, alcohol, caffeine, high fat, and spicy foods * Increase fluids, dietary bulk, and exercise to prevent constipation * Take on an empty stomach * Don’t take at the same time as antacids ## Antiulcer Drugs: Prostaglandin * **Misoprostol (Cytotec)** * **Uses:** Prevention and treatment of peptic ulcers. Pregnancy termination, and labor induction * **Mech of action:** Suppresses gastric acid secretion, and increases cytoprotective mucous in the GI tract * For patient taking high doses of NSAID’s for long term therapy, misoprostol is recommended as an adjunct for the duration of NSAID therapy * **Contraindicated in pregnancy!** * Given po four times per day with meals, and at bedtime * For women of childbearing age: * Negative pregnancy test required < 2 weeks before start of therapy * Patient capable of complying with effective contraception * Oral, and written instructions understood re: warnings of hazards to fetus and danger of sharing medication with others * Start med on 2nd or 3rd day of next normal menstrual period ## Digestive Enzymes * **Pancrelipase saliva substitute** * Digestive enzymes such as substitute saliva and pancreatic enzymes may be needed if normal enzyme levels are very low and proper digestion cannot take place. * Patients receiving replacement enzymes will need to be monitored to ensure that the dose is correct for their particular situation to avoid adverse effects. ## Happy Studying!