Comprehensive Textbook Chapter β Anatomy, Physiology, Disorders & Nursing Care
The gastrointestinal (GI) system consists of the mouth, esophagus, stomach, small intestine, large intestine, and the accessory organs: liver, gallbladder, pancreas, and the ductal system. Its primary function is digestion β the mechanical and chemical breakdown of food into absorbable nutrients β and elimination of waste.
Contains salivary glands that produce saliva (alkaline pH) containing salivary amylase, which begins carbohydrate digestion. The mouth mechanically breaks down food via mastication.
A collapsible muscular tube ~10 inches long with no secretory glands. Alkaline pH from salivary amylase. The lower esophageal sphincter (LES / cardiac sphincter) prevents reflux of gastric contents.
Located in the left hypochondriac, epigastric, and umbilical regions. Parts: cardia, fundus, body, antrum. Two sphincters β cardiac (prevents reflux) and pyloric (regulates emptying into duodenum).
Gastric secretions:
Phases: Cephalic (smell, taste, chewing) and Gastric (presence of food). Chyme = partially digested food leaving the stomach. The stomach is acidic in pH.
Includes duodenum, jejunum, and ileum. Extends from pylorus to ileocecal valve. Microscopic structures:
Chyle = fully digested food in absorbable form.
Divided into cecum, colon (ascending, transverse, descending, sigmoid), rectum, and anus. Appendix attached to cecum. Responsible for water and electrolyte absorption. Normal flora produces vitamin K and ammonia (converted to urea by liver).
Largest internal organ and gland. Located in right hypochondriac and epigastric regions. 4 lobes: right, left, caudate, quadrate. Supplied by portal artery and portal vein. Functional units = lobules formed of hepatic cells.
Functions:
Stores and concentrates bile. Bile is dark green to yellowish-brown, alkaline (pH), composed of 85% water, 10% bile salts, 3% mucus/pigments, 1% fat, 0.7% inorganic salts, 0.3% cholesterol.
Bile duct: hepatic duct + cystic duct = common bile duct (CBD). CBD joins pancreatic duct = hepatopancreatic duct (HPD). Drains into duodenum via Ampulla of Vater (controlled by sphincter of Oddi). Release stimulated by CCK-PZ (cholecystokinin-pancreozymin) from duodenal mucosa.
Bile acid sequestrants (cholestyramine / Questran, colestipol / Colestid) bind bile acids in intestine, preventing reabsorption and forcing liver to use more cholesterol.
Located in left hypochondriac region (head, body, tail). Both exocrine and endocrine functions.
Exocrine: pancreatic enzymes β amylase (carb digestion), lipase (fat digestion), trypsinogen & chymotrypsin (protein digestion). Also secretes sodium bicarbonate to neutralize HCl.
Endocrine: Islets of Langerhans β alpha cells (glucagon), beta cells (insulin).
Sequence: Inspection β Auscultation β Percussion β Palpation
| Test | Normal Value |
|---|---|
| Ammonia | 11β35 ΞΌmol/L |
| Alkaline phosphatase | 20β90 U/L |
| Bilirubin (direct/conjugated) | 0.1β0.4 mg/dL |
| Bilirubin (indirect/unconjugated) | 0.2β0.7 mg/dL |
| Bilirubin (total) | 0.3β1.1 mg/dL |
| SGOT (AST) | 5β20 U/L |
| SGPT (ALT) | 5β35 U/L |
| Prothrombin Time (PT) | 12β14 seconds |
| Serum amylase | 50β150 U/dL |
| Serum lipase | 10β140 U/L |
| AFP (alpha-fetoprotein) | < 10 ng/mL in adults |
Oral Cholecystography (OCG): Oral iodine dye β X-rays. Pre: check iodine sensitivity, administer dye (Telepaque/Oragrafin) 10β12 hours before, NPO after dye. Post: normal diet high in fat may be given; β fluids; monitor for N/V/D.
ERCP: Dye injected via endoscope into hepatopancreatic duct β fluoroscopic X-ray. Pre: NPO 6β8 hours, local anesthesia/sedation. Post: monitor gag reflex and signs of perforation.
Percutaneous transhepatic cholangiography: Percutaneous dye injection into biliary system. Pre: NPO 6β8 hours, sedation. Post: monitor for perforation, peritonitis, septicemia.
HIDA scan: Nuclear imaging; radioactive tracer injected IV β liver β biliary system. If gallbladder not visualized in 4 hours, indicates cholecystitis/cholelithiasis.
Detects H. pylori. Patient ingests carbon-labeled urea; breath sample 10β20 minutes later detects COβ produced by bacterial conversion.
Procedure: Explain, encourage mouth breathing to relax abdomen. Hang solution 30β45 cm (12β18β³). Insert lubricated tube 3β4β³ (7.5β10 cm) without force. Deliver over 5β10 min. Stop for cramping; slow speed. Monitor for cramps, nausea, dizziness, bradycardia.
Indications: Feeding, gastric decompression, gastric analysis.
Types: Levin tube (single lumen, non-vented) | Salem-Sump tube (double lumen, vented).
Procedure: Semi-to-high Fowler's. NEX measurement. Lubricated tube into most patent nostril. Sips of water to facilitate swallowing. Initially extend neck slightly; when past oropharynx, bend chin forward. X-ray confirms position + pH of aspirate.
Nursing care: Monitor patency, assess for distention/N/V, turn side-to-side if not draining. Frequent mouth care. Elevate HOB 30β45Β° during and 1β2 hours after feeding. Monitor fluid/electrolyte balance.
Catheter through abdominal incision into stomach. Feeding: bolus, continuous (24h), or cyclical (8β16h).
IV administration of complete nutrition (dextrose, amino acids, lipids, electrolytes, vitamins, trace elements) for patients unable to tolerate enteral feeding. Requires central line (PICC or subclavian). Nursing: strict asepsis, monitor blood glucose, daily weights, I&O, check for infection.
Pathophysiology: Backflow of gastric contents into esophagus due to incompetent LES, pyloric stenosis, or reduced gastric motility.
Signs & Symptoms: Pyrosis (heartburn), dyspepsia, regurgitation, hypersalivation.
Diagnostics: Esophagoscopy, barium swallow, esophageal pH monitoring.
Medical Management:
Nursing Care: Small frequent meals, upright position during and after meals, weight reduction if obese.
Pathophysiology: Inflammation and breakdown of gastric protective barriers β HCl diffuses into gastric lumen β hemorrhage, ulceration, adhesions.
S/S: Anorexia, N/V, belching, hematemesis, epigastric tenderness, β Hgb/Hct. Confirmed by endoscopy and gastric analysis.
Management: Antiemetics, antacids. NPO until tolerating, then bland diet. Avoid coffee, spicy foods, alcohol, NSAIDs, steroids.
Pathophysiology: Ulceration of mucosal lining of stomach, duodenum, or esophagus. Causes: smoking, alcohol, stress, NSAIDs/steroids, H. pylori infection.
| Feature | Gastric Ulcer | Duodenal Ulcer |
|---|---|---|
| Location | Usually in antrum | Within 2 cm of duodenum |
| Acidity | Normal; rapid acid diffusion into mucosa | Hyperacidity with increased gastric emptying |
| Pain | Mid/left epigastric, sharp; 1β2 hours after meals; worsened by food | Burning/cramping; 2β4 hours after meals & at night; relieved by food |
| Weight | Weight loss | Weight gain |
Findings: Epigastric pain, bloating, hematemesis, melena. Complications: perforation, peritonitis, strictures.
Diagnostics: Gastric analysis, endoscopy, urea breath test.
Medical Management:
Surgical Management: Vagotomy, antrectomy, pyloroplasty, Billroth I (gastroduodenostomy), Billroth II (gastrojejunostomy), partial/total gastrectomy.
Nursing Care for Active Bleeding: Monitor VS closely, NPO + IV fluids, NG lavage (NS or tap water), vasopressin as ordered.
Post-Gastrectomy Care: Monitor for Bββ deficiency, hemorrhage, postprandial hypoglycemia, dumping syndrome.
Pathophysiology: Inflammation of stomach and intestines caused by viral, bacterial, or parasitic infection; food poisoning; or toxins.
S/S: N/V/D, abdominal cramps, fever, dehydration, electrolyte imbalances.
Management: Fluid/electrolyte replacement, antiemetics, antidiarrheals (bismuth subsalicylate, loperamide). Gradual introduction of bland, high-protein, low-fat, low-bulk diet. Avoid milk products. Prevent anal excoriation.
Pathophysiology: Autoimmune disorder; chronic inflammation from gluten (protein in barley, rye, oats, wheat) damages small intestinal villi β malabsorption of fat and fat-soluble vitamins (A, D, E, K).
S/S: Steatorrhea, failure to thrive, anemia, distended abdomen, abdominal pain, irritability, vomiting, muscle wasting.
Diagnostics: Jejunal/duodenal biopsy (villous atrophy). Rule out cystic fibrosis.
Management: Lifelong gluten-free diet (no BROW β barley, rye, oats, wheat). Can eat rice, millet, corn, soy, potato. Fat-soluble vitamins in water-soluble form. TPN for severe malnourishment.
Pathophysiology: Chronic inflammatory bowel disease with granuloma formation β thickening, narrowing, scarring of intestinal wall. Lesions are intermittent and transmural. Usually affects terminal ileum, cecum, ascending colon. Remissions and exacerbations.
S/S: 3β4 semi-soft stools with mucus/pus, A/N/V, weight loss, RLQ pain, dehydration, pallor, increased peristalsis, electrolyte imbalance.
Diagnostics: Barium enema, sigmoidoscopy, colonoscopy, video capsule endoscopy (VCE).
Management: Antibiotics, corticosteroids, antidiarrheals, adalimumab (Humira), anticholinergics, iron supplements, TPN. Diet: high-calorie, high-protein, low-residue β no milk/milk products, no gas-producing foods (cabbage, broccoli, cauliflower, legumes, onion, corn, nuts). Surgery for severe cases.
Pathophysiology: Inflammation of colon β ulceration, edema, thickening, scarring, β absorptive capacity. Begins in rectum and spreads upward (continuous lesions). Affects mucosal and submucosal layers. Remissions and exacerbations.
S/S: Severe diarrhea (15β20 liquid stools/day with blood, mucus, pus), tenesmus, weight loss, abdominal cramps, anorexia, weakness, dehydration, low-grade fever, colon tenderness.
Management (mildβmoderate): Low-residue, high-protein diet; no milk/products or gas-forming foods; antibiotics, corticosteroids, anticholinergics, antidiarrheals, immunosuppressives; 5-ASA compounds (mesalamine / Asacol, sulfasalazine / Azulfidine).
Severe: NPO + IVF, blood transfusions, NG suction, surgery (total proctocolectomy with permanent ileostomy).
Pathophysiology: Diverticulum = outpouching of intestinal mucosa. Diverticulitis = inflammation of diverticulum. Most frequent in sigmoid colon.
S/S: Intermittent LLQ pain (worse with coughing/straining), alternating constipation/diarrhea with blood/mucus, palpable tender rectal mass, N/V, flatulence, fever, distention.
Management: High-residue diet (diverticulosis), low-residue diet (diverticulitis). Bulk-forming laxatives, anticholinergics, antibiotics. Surgery (temporary/permanent colostomy) for severe cases.
Pathophysiology: Inflammation of appendix preventing mucus drainage into cecum β ischemia β gangrene β rupture β peritonitis.
S/S: RLQ pain at McBurney's point (β distance from ASIS to umbilicus). N/V, guarding, walks stooped over, rebound tenderness, decreased bowel sounds. Psoas sign & Rovsing's sign. β WBC, fever.
Management: No enema, laxatives, or heating pad (risk of perforation). Antibiotics, antipyretics. Minimal analgesics until diagnosis confirmed. Surgery: laparoscopic (uncomplicated) or open (if perforation suspected with Penrose drain).
Nursing: Semi-Fowler's or right side to promote drainage. Monitor drain and NG suction.
Pathophysiology: Inflammation of liver β hepatic cell degeneration, necrosis, Kupffer cell proliferation β interrupted bile flow β jaundice.
Phases: Preicteric (A/N/V, fatigue, weight loss, hepatomegaly, RUQ discomfort, splenomegaly) β Icteric (jaundice, pruritus, light stool, dark urine) β Posticteric (improving sense of well-being).
| Type | Transmission | Incubation | Prevention |
|---|---|---|---|
| Hep A | Fecal-oral; contaminated food/water | 2β6 weeks | Vaccine (Havrix); immunoglobulin post-exposure |
| Hep B | Blood/body fluids, sexual, parenteral | 6β24 weeks | Vaccine (Engerix B); HBIg post-exposure |
| Hep C | Primarily blood | 5β10 weeks | No vaccine available |
| Hep D | Blood (co-infection with Hep B) | 7β8 weeks | Hep B vaccine may prevent |
| Hep E | Contaminated food/water | 2β9 weeks | Hand washing |
Nursing Management: Monitor for fulminant hepatitis and hepatocellular carcinoma. High-carb, high-vitamin, moderate-to-high protein, low-fat diet in small frequent meals. Antiemetics 30 min before meals. Pruritus care: no soap, lukewarm baths, emollients, cool clothing, short nails, cool compresses. Discharge: transmission prevention, avoid alcohol/hepatotoxic drugs, balance rest/activity, no blood donation.
Pathophysiology: Chronic progressive liver disease β inflammation, fibrosis, degeneration β scar tissue β malfunction.
Types: Laennec's (alcohol-related), NAFLD, post-necrotic (viral hepatitis), cardiac (R-sided CHF), biliary (CBD obstruction).
S/S: A/N/V, flatulence, indigestion, fatigue, hepatomegaly, RUQ pain, ascites, mental status changes, gynecomastia, β sex hormones, jaundice, pruritus, pancytopenia (β infection risk, easy bruising β spider angiomas, palmar erythema), muscular atrophy.
Diagnostics: β SGOT, SGPT, LDH, alkaline phosphatase, bilirubin. Prolonged PT. β Hgb, Hct, albumin.
Nursing Care: Small frequent feedings β high-calorie, high-carb, low-to-moderate protein, low-fat. Reverse isolation for severe leukopenia. Prevent bleeding: avoid straining, nose blowing, coughing, Valsalva, NG tube. Diuretics for ascites. Avoid hepatotoxic drugs and alcohol.
Patho: Hypoalbuminemia + portal hypertension + hyperaldosteronism β fluid leaks into peritoneal cavity. S/S: Shifting dullness, fluid thrill, protruding umbilicus, distention, striae, peripheral edema, SOB. Management: KβΊ-sparing diuretics, albumin infusion, paracentesis, LeVeen shunt. Restrict fluid 1000β1500 mL/day, NaβΊ 200β500 mg/day.
Dilated esophageal veins from portal hypertension. S/S: Hematemesis, melena, fatigue, ascites, caput medusae. Management: Iced NS lavage, blood transfusions, vitamin K, octreotide (Sandostatin), sclerotherapy, vasopressin, Sengstaken-Blakemore tube. Nursing: semi-Fowler's, maintain traction, label lumens, deflate balloons as ordered, keep scissors at bedside.
Terminal complication β liver cannot convert ammonia to urea β ammonia diffuses to brain. Early signs: mental status changes (irritability, confusion, insomnia), slurred speech, tremors, hyperactive reflexes, positive Babinski. Progressive: asterixis, disorientation, apraxia, fetor hepaticus (fruity/musty breath). Late: coma, absent reflexes. Management: High-carb, low-fat, protein-free diet; lactulose (decreases ammonia), neomycin. Nursing: protect from injury, eye care, avoid drugs detoxified by liver.
Pathophysiology: Proteolytic/lipolytic enzymes activated in pancreas instead of duodenum β autodigestion. Precipitated by alcoholism, biliary tract disease, cholelithiasis, trauma, viral infection, duodenal ulcer, hyperlipidemia.
S/S: Mid-epigastric or LUQ pain radiating to back/flank/substernal area. Pain aggravated by eating (high-fat or alcohol). Dyspnea, N/V, steatorrhea, β/absent bowel sounds, tenderness/guarding. Grey Turner's spots (flank ecchymosis), Cullen's sign (periumbilical ecchymosis). Hypocalcemia. β serum amylase & lipase, β blood sugar.
Management: NPO. Narcotic analgesics (hydromorphone / Dilaudid, fentanyl). Smooth muscle relaxants (nitroglycerine, papaverine). Anticholinergics, antacids, antihistamines, calcium gluconate. Fetal position for comfort. When tolerating: high-carb, high-protein, low-fat diet, small frequent feedings. Avoid caffeine.
Pathophysiology: Acute/chronic inflammation of gallbladder, often with gallstones (cholesterol or pigment stones).
Risk factors: Women > 40, Caucasian, obese, post-menopausal on ERT, OCP users.
S/S: Epigastric/RUQ pain radiating to scapula (2β4 hours after meals), fatty food intolerance, positive Murphy's sign, guarding, rigidity, rebound tenderness, fever, tachycardia, pruritus, jaundice, dark urine, clay-colored stool, steatorrhea.
Diagnostics: β amylase, lipase, WBC, alkaline phosphatase, direct bilirubin. OCG, ultrasound, HIDA scan.
Medical Management: Narcotics (hydromorphone, fentanyl), anticholinergics, antiemetics. Bile acid sequestrants for itching. Stone dissolution: ursodiol (Actigall), chenodiol (Chenix). ECSWL.
Surgical: Cholecystectomy (laparoscopic or open). T-tube inserted if CBD explored. Post-op T-tube care: closed gravity drainage, semi-Fowler's, expect 700β1000 mL bile-colored drainage first 24 hours, keep skin clean/dry, t-tube cholangiogram before removal.
Mechanical: Volvulus, intussusception, hernias, foreign bodies, neoplasms, fecal impaction.
Neurogenic (paralytic ileus): Abdominal surgery, peritonitis, shock, spinal cord injury, electrolyte imbalance.
Vascular: Embolus, atherosclerosis β ischemia and gangrene.
S/S (small bowel): Colicky intermittent pain, non-fecal vomiting. Large bowel: Cramp-like pain, occasional fecal vomiting, lack of flatus, absolute constipation. General: distention, rigidity, high-pitched bowel sounds above obstruction, β/absent below. Diagnosis: flat plate X-ray. Management: decompression, enema, surgery.
Upper GI bleed: Hematemesis (coffee-ground emesis), melena (tarry black stools). Causes: PUD, gastritis, esophageal varices, Mallory-Weiss tear.
Lower GI bleed: Hematochezia (bright red blood per rectum). Causes: diverticulitis, colitis, colorectal cancer, hemorrhoids.
Nursing: Monitor VS, NPO, IV access, NG tube for lavage/diagnosis, type & crossmatch for transfusion, monitor Hgb/Hct, administer PPIs, vasopressin, octreotide as ordered.
2nd most common cancer in men & women. Peak age 50β60. Risk factors: chronic IBD (diverticulosis, UC), family history of polyps (FAP).
S/S: Alteration in bowel pattern, abdominal cramps/distention, weight loss, pallor, unexplained anemia. Diagnosis: CEA positive, positive stool OB, β Hgb/Hct, barium enema, digital rectal exam, sigmoidoscopy, biopsy.
Management: Radiation, chemotherapy, surgery.
Action: β acid production by suppressing parietal cells. Nursing: Take before meals, swallow whole. Antacids may be taken with PPIs.
Action: β gastric acid secretion. Nursing: Give Β½ hour before meals & bedtime. Cimetidine: reversible leukopenia, confusion β monitor CBC.
Nursing: 1β2 hours after meals & bedtime. Separate 1 hour from other drugs.
Given for pancreatic insufficiency (chronic pancreatitis, cystic fibrosis). Administer with meals/snacks. Do not crush or chew. Monitor for steatorrhea improvement.
| Condition | Key Features | Management |
|---|---|---|
| Esophageal Atresia / TEF | Polyhydramnios, inability to pass NG tube, drooling, regurgitation, choking/aspiration, distended abdomen | Surgical repair; gastrostomy feeding; prevent aspiration |
| Pyloric Stenosis | Olive-shaped mass, projectile non-bilious vomiting at 3β4 weeks, visible peristalsis, metabolic alkalosis | Pyloromyotomy; post-op: glucose water β formula in 24h |
| Intussusception | Piercing cry, sausage-shaped mass, currant-jelly stool; peak 6 months | Barium enema (diagnostic + therapeutic up to 3Γ); surgical resection if fails |
| Hirschsprung's Disease | Failure to pass meconium, ribbon-like stools, bile-stained vomiting, failure to thrive; aganglionic megacolon | Colostomy (palliative); pull-through procedure (corrective) |
| Celiac Disease | Gluten intolerance β villous atrophy, steatorrhea, FTT, ADEK deficiency | Lifelong gluten-free diet (no BROW) |
| Cleft Lip/Palate | Feeding difficulty, nasal regurgitation, otitis media risk | Cheiloplasty (~2 months); Palatoplasty (~9β12 months); special feeding techniques |