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• The digestive system consists of the gastrointestinal tract and its accessory organs.

Functions of the Digestive System

• All cells require nutrients obtained from food, including proteins, fats, carbohydrates, vitamins, and minerals.
• The GI tract's major functions consist of:
  • Breaking down food particles for digestion.
  • Absorbing small nutrient molecules into the bloodstream.
  • Eliminating undigested food and waste products.
• After ingestion, food moves through the GI tract, interacting with secretions that aid digestion, absorption, or elimination.

Digestion

• Digestion involves both mechanical and chemical processes.

Mechanical Digestion

• Chewing in the mouth breaks down food.
• Swallowing moves food through the esophagus.
  • This involuntary phase is controlled by the medulla oblongata. The epiglottis covers the trachea to prevent aspiration.
• Churning in the stomach mixes food.
• Segmentation contraction occurs in the small intestine.

Chemical Digestion

• In the mouth, ptyalin/salivary amylase from parotid, submaxillary, and sublingual glands begins digestion.
• The stomach partially digests food into chyme, taking 30 minutes to hours.
  • Hydrochloric acid, secreted by glands in the stomach, has a pH of 1, chemically digesting food and destroying bacteria.
  • Pepsin digests protein.
  • Intrinsic factor is needed for Vitamin B12 absorption in the ileum.
• The small intestine takes 3-6 hours.
  • The duodenum receives digestive secretions from the pancreas, liver, and gallbladder.
  • Pancreatic secretions neutralize acidic chyme with bicarbonate and contain trypsin (for protein), amylase (for starch), and lipase (for fats).
  • Bile emulsifies fats; it is produced by the liver and stored in the gallbladder.
  • Nutrient absorption occurs in the small intestine.
• The colon/large intestine, in terms of chemical digestion:
  • Has colonic secretions of electrolyte solution (alkaline) and mucus added to residual material.
  • Reabsorbs water and electrolytes.
  • Contains gut microbiome/microbiota for protection, defense, and vitamin synthesis.

Excretion

• Feces consist of undigested food, inorganic materials, water, and bacteria.
  • Feces is about 75% fluid and 25% solid material.
  • The brown color is due to bile breakdown by intestinal bacteria.
  • Odor results from chemicals formed by intestinal bacteria.

Age-Related Changes in the Gastrointestinal System

• Oral Cavity and Pharynx
  • Structural Changes: Injury/loss or decay of teeth, atrophy of taste buds, reduced saliva production reduced ptyalin and amylase in saliva.
  • Implications include difficulty chewing and swallowing.
• Esophagus
  • Structural changes of decreased motility and emptying, weakened gag reflex, and decreased resting pressure of the lower esophageal sphincter.
  • Implications include reflux and heartburn.
• Stomach
  • Structural changes include degeneration and atrophy of gastric mucosal surfaces with decreased production of HCl, decreased secretion of gastric acids and digestive enzymes, and decreased gastric motility and emptying.
  • Implications include food intolerances, malabsorption, or decreased vitamin B12 absorption.
• Small Intestine
  • Structural changes include atrophy of muscle and mucosal surfaces, thinning of villi and epithelial cells.
  • Implications include decreased motility and transit time, leading to indigestion and constipation.
• Large Intestine
  • Structural changes of decreased mucus secretion, decreased elasticity of rectal wall, decreased tone of internal anal sphincter, and slower/duller nerve impulses in the rectal area.
  • Implications include decreased motility and transit time, indigestion and constipation; decreased absorption of nutrients such as dextrose, fats, calcium, and iron; fecal incontinence.

Common Symptoms Leading Patients to Seek Healthcare

• Abdominal Pain
• Dyspepsia
• Gas
• Nausea and Vomiting
• Diarrhea
• Constipation

Pain Assessment

• Pain is an unpleasant sensory and emotional experience related to actual or potential tissue damage.

Categories of Pain

• Acute Pain: Involves tissue damage, is of short duration, and is expected to resolve with normal healing.
• Chronic/Persistent Pain: May be cancerous or non-cancerous, intermittent with flares, or continuous.
  • Some cancer patients experience breakthrough pain (BTP), where continuous chronic pain is accompanied by intense acute exacerbations.
• Nociceptive Pain: Normal processing of stimuli that damages tissues, or has the potential to do so if prolonged.
  • Somatic pain arises from bone, joint, muscle, skin, or connective tissue, described as aching or throbbing.
  • Visceral pain arises from visceral organs such as the GI tract and pancreas, and can be due to tumor involvement or obstruction.
• Neuropathic Pain: Abnormal processing of sensory input by the peripheral or central nervous system.

Pain Evaluation

• Location: Ask the patient to state where they feel the pain.
• Quality: Ask the patient describe the pain by type (Sharp, shooting, burning)
• Onset and Duration: Determine the onset and duration of pain.
• Aggravating and relieving factors: Identify what makes the pain better or worse.

Pain Intensity Scales

• Numeric Rating Scale (NRS): Patients rate pain from 0-10.
• Wong Baker FACES Pain Rating Scale: Uses six cartoon faces with descriptors, can be used for children 3+ and adults.
• FLACC: Used for young children (0-2), assigning scores (0-10) based on facial expression, leg movement, activity, crying, and consolability.
• CPOT (Critical Care Pain Observation Tool): Used for patients in critical care who cannot self-report pain.

Reassessment of Pain Medications

• Reassess with each new report of pain.
• Reassess before and after administration of analgesic treatment.
  • Generally, reassess 15-30 minutes after parenteral administration.
  • Reassess 1-2 hours after oral administration.

Abdominal Discomfort

• Upper abdominal discomfort associated with eating commonly called indigestion is the most common symptom of patients with GI dysfunction.
• Dyspepsia: Indigestion is an imprecise term that refers to a host of upper abdominal or epigastric symptoms such as pain, discomfort, fullness, bloating, early satiety, belching, heartburn, or regurgitation.

Intestinal Gas

• Accumulation of gas in the GI tract can result in belching, the expulsion of gas from the stomach through the mouth, and flatulence, expulsion of gas from the rectum.
• Patients may complain of bloating, distention, or feeling "full of gas” with food intolerance or gallbladder disease.

Nausea and Vomiting

• Nausea: A vague, uncomfortable sensation of sickness.
• Vomiting: Forceful emptying of the stomach and intestinal contents.
  • Emesis/vomitus may contain undigested food, hematemesis, or bilious materials.
  • Acute onset of emesis with bright-red or coffee ground color could indicate upper GI bleeding.
• Distention of the upper GI tract and duodenum can cause both symptoms, but is also an early sign of disease.
• Odors, activity, medications, or food can trigger them.

Changes in Bowel Habits

These signal colonic dysfunction or disease.

• Diarrhea: An increase in the frequency and liquidity of stool, or in daily stool weight or volume. Commonly occurs when contents travel too rapidly, limiting time for absorption/reabsorption.
• Constipation: Decrease in frequency of stool or stools that are hard, dry, and of smaller volume than typical; may be associated with anal discomfort and rectal bleeding.
• Stool is normally light to dark brown, but color can be affected by disease or food/medications.
  • Green stool from leafy green vegetables.
  • Red from beets, red gelatin, or tomato soup
  • Black stool from black licorice, bismuth, or Iron intake.
  • Milky white from Barium contrast agent.
• Blood in the Stool
  • Black and tarry stool means there is upper GI Tract Bleeding
  • Dark red means there is lower GI Tract Bleeding
  • Streaking of bood may indicate rectal/anal bleeding
• Other Abnormalities of Stool
  • Bulky, greasy, foamy stools that are foul in odor and may or may not float Light gray or clay-colored stool, caused by a decrease or absence of conjugated bilirubin
  • Stool with mucus threads or pus is an abnormal texture Small, dry, rock-hard masses occasionally streaked with blood
  • Loose or watery, may or may not be streaked with blood

Abdominal Assessment

• Assessment of bowel sounds uses a stethoscope to hear clicks and gurgles (5-30/min). Bowel sounds are designated as normal, hypoactive, hyperactive, or absent. A loud prolonged gurgle known as borborygmus indicates "stomach growling".

Diagnostic Tests

• Serum Laboratory Tests: Liver function tests and evaluation of tumor markers or the prothrombin time.
• Stool Tests: Inspecting consistency, color, and occult blood. Additional studies check for fecal urobilinogen, fat, nitrogen, Clostridium difficile, leukocytes, stool osmolar gap, parasites, pathogens, food residues, etc.
• Breath Tests: Hydrogen tests measure carbohydrate absorption and bacterial overgrowth while urea tests detect H. pylori.
• Abdominal Ultrasonography: A noninvasive diagnostic technique using high-frequency sound waves to image internal structures. Useful in detecting gallbladder, pancreas, or ovarian enlargements, gallstones, ectopic pregnancy, or appendicitis.
  • Patients should fast 8–12 hours and those undergoing gallbladder studies should eat a fat-free meal. Barium studies should be performed after as barium interferes with sound wave transmission. Observe sedated patients for an hour afterward for their ability to ambulate.

Endoscopic Procedures

• Upper Gastrointestinal Fibroscopy/Esophagogastroduodenoscopy: A 30-minute viewing process that can be for theraputic purposes.
• Colonoscopy: Fiberoptic instruments inspect the large intestine over the one hour procedure. This process can capture video, biopsies, and remove polyps for aid and screening. Left side-lying positions with legs drawn towards the chest are to be used.
  • Nursing Considerations include Colon cleansing with laxatives two nights before, enemas until clear on the test.
  • PEG solutions commonly cleanse the colon with a clear liquid and Diet a day before the procedure.

Colonscopy Complications

• Cardiac arrhythmias and respiratory depression may cause vasovagal reactions and overload or hypotension from bowel prep.
• Bowel perforation can occur during this procedure.
• Monitor rectal bleeding, abdominal pain or distention, fever, focal peritoneal signs post-procedure.
• A side effect of the amnesic, Midazolam, and need for written instructions and patients to report bleeding is emphasized.

Additional Endoscopies

• Anoscopy, Proctoscopy, and Sigmoidoscopy: Endoscopic examination of the anus, rectum, sigmoid is used to evaluate chronic diarrhea, fecal incontinence, ischemic colitis, and lower GI hemorrhage and other pathologic processes.
  • Warm water or Fleet enemas are used to prepare the bowels, without restricting diet or sedatives
  • Monitor for rectal bleeding and signs of intestinal perforation.
• Laparoscopy (Peritoneoscopy): Visualization of intra-abdominal organs by injecting carbon dioxide into the peritoneal cavity.

Disorders of the Salivary Glands

• Parotitis: Inflammation of the parotid gland can be epidemic caused by mumps, or bacterial by staphylococcus. Sudden onset associated with signs of systemic infection, such as fever, pain in the ear, and red, shiny swelling.
  • Medical Management: Cold packs, proper nutrition/fluids, good oral hygiene, medication changes, and antibiotics. A parotidectomy may be needed is antibiotics are ineffective.
• Sialadenitis: Inflammation caused by infection, dehydration, radiation, stress, malnutrition and bad oral hygiene. Sialogogues relieve by triggering saliva flow and Sialendoscopy is used to visualize the gland.
• Sialolithiasis: Calculi stones in the submandibular gland composed of calcium Phosphate.

Additional Oral Care

• Stomatitis/Oral Mucositis: Mouth ulcers induced by chemotherapy. Use of Saline/sodium bicarbonate rinses of 1/2 to 1 tsp of baking soda: 8 oz of warm water. 1/4 tsp salt: 8oz of warm water

Disorders of the Esophagus

• Achalasia: Rare disorder of absent or ineffective peristalsis of the distal esophagus and lower esophageal sphincter.
  • Symptoms: Dysphagia with solid food, sticking in chest, regurgitation of undigested food along with chest or epigastric pain.
  • X-ray may note a bird-beak deformity above the lower gastroesophageal sphincter.
  • Achalasia can be managed through Pneumatic dilation requiring about 2 dialations and Esophagomyotomy to cut the muscle fibers.
• Esophageal Spasm:
  • Jackhammer esophagus has spasms in 20%+ swallows at high amplitude Diffuse esophageal spasm (DES) – normal in amplitude and premature, uncoordinated Type III (spastic) achalasia – has sphinter obstruction and spasms. Managed with smooth muscle relaxants and Proton Pump Inhibitors
• Hiatal Hernia:
  • Opening in the diaphragm which the esophagus passes becomes enlarged, and part of the upper stomach moves into the lower portion of the thorax
• Two (2) Types: Sliding or Paraesophageal Xray studies and barium swallow are used to dignose. Adminsiter small feedings and elevate head of bed to treat.
• Diverticulum: Diagnosis is done via Barium Swallow. Management is completed through surgery Barium Swallow is used. No endoscopy for risk of perforation and must complete management through surgicaly.
• Gastroesophageal Reflux Disease (GERD): Backflow of contents where pyrosis and regurgitation occurs. May be caused by an incompetent lower esophogeal sphinter, increase with age or other diseases, and associations with tobacco, coffe, alcohol, or bacterium intake. May lead to dental erosion and ulcerations The GOLD test for is PH level monitoring and Proton Pump Inhibitor testing. Lifestyle Modification, Pharmacologic and surgery can treat. 2/8/2025 Lifestyle Modification, Pharmacologic and surgery can treat.
• Barrett Esophagus; A changed conditions in the esopagus from family, EAC, GERD, smoking, and obesity. This may cause heartburn. If Dysplasia occurs, endoscopic and high-frequency ablation are done.
• Disorders of the sotmach include Gastrisis from acute or repeated infections. 2/8/2025
• Disorders of the stomach include Gastritis from acute or repeated infections. Promote diet and limit irritants. May be caused by bacterias antibiotics can treat this. 2/8/2025
• Infections from Gastritis can cause irritation and may be treated using antibiotics prescribed by a practitioner or given to patients on NSAIDs.