Digestion

Definition

Digestion is the mechanical and chemical breakdown of food into smaller molecules (amino acids, monosaccharides, fatty acids) that can be absorbed across the intestinal mucosa into circulation.

Process

1. Oral: Mastication, amylase begins carbohydrate digestion.
2. Gastric: HCl and pepsin denature/hydrolyze proteins.
3. Small intestinal: Pancreatic enzymes (amylase, lipase, protease) and bile complete digestion and absorption (duodenum, jejunum).
4. Colonic: Water and electrolyte reabsorption; stool formation.

Disorders of Digestion

Celiac disease (gluten enteropathy), lactose intolerance, pancreatic insufficiency (cystic fibrosis, pancreatitis), IBS, Crohn's disease, short bowel syndrome.

Nursing Considerations

Assess weight, dietary intake, bowel function, labs (albumin, prealbumin, vitamin levels). Provide nutritional counseling, enzyme replacement (pancrelipase with meals for CF/pancreatic insufficiency), lactose-free diet, or gluten-free diet as indicated.

NCLEX Relevance

Expect GI content in malabsorption, pancreatic disease, and inflammatory bowel disease scenarios.