Assessment of Digestive and Gastrointestinal Function Study Notes

Assessment of Digestive and Gastrointestinal Function

1. Organs of the Digestive System

  • Parotid gland

  • Pharynx

  • Oral cavity (mouth)

  • Sublingual gland

  • Submandibular gland

  • - Trachea

  • Esophagus

  • Diaphragm

  • Liver

  • Gallbladder

  • Common bile duct

  • Duodenum

  • Pancreatic duct

  • Ascending colon

  • Vermiform appendix

  • Stomach

  • Spleen

  • Pancreas

  • Transverse colon

  • Small intestine

  • Descending colon

  • Sigmoid colon

  • Rectum

  • Anus

2. Anatomy and Blood Supply of the Large Intestine

  • Major arteries:

    • Superior mesenteric artery

    • Inferior mesenteric artery

    • Aorta

3. Functions of the Digestive Tract

  • Breakdown of food for digestion

  • Absorption of small nutrient molecules produced by digestion into the bloodstream

  • Elimination of undigested and unabsorbed foodstuffs and other waste products

4. Terms Related to Digestive Processes

  • Digestion: Begins with chewing, breaking down food into smaller particles to be swallowed and mixed with digestive enzymes.

  • Absorption: Major function of the small intestine, where vitamins and minerals are absorbed essentially unchanged. Absorption begins in the jejunum through active transport and diffusion across the intestinal wall into circulation.

  • Elimination: Occurs post-digestion and absorption when waste products are expelled from the body.

5. Major Enzymes and Secretions

  • Chewing and swallowing:

    • Saliva

    • Salivary amylase

  • Gastric function:

    • Hydrochloric acid

    • Pepsin

    • Intrinsic factor

  • Small intestine:

    • Amylase

    • Lipase

    • Trypsin

    • Bile

  • Terminology:

    • Chyme (partially digested food)

    • Emulsification (breaking fat into smaller droplets)

    • Peristalsis (wave-like muscle contractions that move food through the digestive tract)

6. Major Digestive Enzymes and Their Sources

TABLE 38-1

Enzyme/Source

Digestive Action

Carbohydrate Digesting Enzymes

Ptyalin (salivary amylase)

Starch → dextrin, maltose, glucose

Amylase

Starch → dextrin, maltose, glucose

Maltase

Maltose → glucose

Sucrase

Sucrose → glucose, fructose

Lactase

Lactose → glucose, galactose

Protein Digesting Enzymes

Pepsin

Protein → polypeptides

Trypsin

Polypeptides → dipeptides, amino acids

Aminopeptidase

Polypeptides → dipeptides, amino acids

Dipeptidase

Dipeptides → amino acids

Fat Digesting Enzymes

Pharyngeal lipase

Triglycerides → fatty acids, diglycerides, monoglycerides

Steapsin

Triglycerides → fatty acids, diglycerides, monoglycerides

Pancreatic lipase

Triglycerides → fatty acids, diglycerides, monoglycerides

Bile

Fat emulsification

7. Major Gastrointestinal Regulatory Substances

TABLE 38-2

Substance

Stimulus for Production

Target Tissue

Effect on Secretions

Effect on Motility

Acetylcholine

Stomach distention, vagal and local nerves

Gastric glands, other secretory glands, gastric and intestinal muscle

↑ Gastric acid

Generally increased

Norepinephrine

Stress, other various stimuli

Secretory glands, gastric and intestinal muscle

Generally inhibitory

Generally decreased; increased sphincter tone

Gastrin

Vagal stimulation, calcium containing foods

Gastric glands, stomach antrum, duodenum

↑ Secretion of gastric acid and pepsinogen

Increased motility of stomach; stimulates smooth muscle contraction

Cholecystokinin

Presence of chyme in duodenum

Gallbladder, pancreas

Release of bile into duodenum

Slows gastric emptying

Secretin

pH of chyme in duodenum (pH <3)

Pancreas, stomach

↑ Production of enzyme-rich pancreatic secretions

Decreases GI motility

Histamine

Unclear; substances in food

Gastric glands

↑ Gastric acid production

8. Common Manifestations of GI Disease

  • Abdominal pain

  • Dyspepsia (discomfort in the digestive tract)

  • Gas

  • Nausea and vomiting

  • Change in bowel habits and stool characteristics

  • Jaundice (yellowing of skin/eyes)

  • Ascites (fluid buildup in the abdomen)

  • Engorged veins

9. Assessment of the GI System

Health History

  • Information about abdominal pain, dyspepsia, gas, nausea and vomiting, diarrhea, constipation, fecal incontinence, jaundice, and previous GI disease is obtained.

Pain

  • Aspects to consider:

    • Character, duration, pattern, frequency

    • Location

    • Distribution of referred abdominal pain

    • Time of the pain

10. Physical Assessment of the GI System

  • Oral cavity:

    • Lips

    • Gums

    • Tongue

  • Abdominal assessment:

    • Four quadrant method

    • Inspection

    • Auscultation

    • Percussion

    • Palpation

  • Rectal inspection

11. Diagnostic Tests of the GI System

  • Types:

    • Serum laboratory studies

    • Stool tests

    • Breath tests

    • Abdominal ultrasonography

    • Genetic testing

    • Imaging studies (CT, PET, MRI, scintigraphy, virtual colonoscopy)

    • Upper and lower GI tract studies

    • GI motility studies

    • Endoscopic procedures (e.g., EGD, colonoscopy)

Specific Tests

  • H. pylori: Test requires fasting for 8-12 hours; gas or food can affect the results.

  • Colonoscopy and Flexible Fiber-Optic Sigmoidoscopy: Procedures require patient to drink all bowel prep till clear.

12. Liver Function Tests

  • Blood tests include:

    • Measures of serum enzyme activity (serum aminotransferases, alkaline phosphatase)

    • Serum concentrations of proteins (albumin and globulins)

    • Bilirubin, ammonia, and clotting factors

glucogenic function: ammonia converted to urea, elevated in liver failure.

13. Nursing Interventions for GI Diagnostic Tests

  • Inform the primary provider of known medical conditions or abnormal laboratory values that may affect the procedure.

  • Assess hydration adequacy before, during, and after the procedure; educate about hydration maintenance.

  • Provide health information and procedural education to patients and significant others.

  • Offer instructions on post-procedure care and activity restrictions.

  • Help patients cope with discomfort and alleviate anxiety.