DIGESTIVE SYSTEM

Digestion

The mechanical and chemical breakdown of food into forms that can be absorbed by cells.

Mechanical Digestion

Physically breaks food into smaller pieces without changing its chemical composition; examples include chewing and churning.

Chemical Digestion

Uses enzymes to break food molecules into simpler substances, changing the chemical composition and producing nutrients that can be absorbed.

Ingestion

The process of taking in food.

Absorption

The process by which nutrients from food are taken into the cells.

Defecation

The elimination of waste from the body.

Alimentary Canal

The food passageway extending from mouth to anus.

Mucosa

The innermost layer of the alimentary canal wall that provides protection, absorption, and secretion.

Submucosa

The layer of the alimentary canal wall composed of loose connective tissue, blood vessels, lymphatic vessels, and nerves; nourishes tissues and transports absorbed nutrients.

Muscularis (Externa)

The layer composed of circular and longitudinal smooth muscle responsible for mixing and propelling food.

Serosa

The outermost layer of the alimentary canal wall that provides protection and lubrication.

Peristalsis

Wave-like contractions that move food forward through the digestive tract.

Parasympathetic Nervous System

Part of the autonomic nervous system that stimulates digestion and increases secretion and motility.

CCK (Cholecystokinin)

A hormone that stimulates bile release and enzyme secretion from the pancreas.

Villi

Fingerlike projections in the small intestine that increase surface area for absorption.

Gastrin

A hormone that increases gastric juice production.

Chyme

A semifluid mixture of food and gastric juice that passes from the stomach to the small intestine.

Jaundice

Yellowing of the skin and eyes due to bile duct blockage, hepatitis, or cirrhosis.

Gallstones

Crystalized cholesterol that forms in the gallbladder, causing pain and complications.

Diverticulosis

Outpouchings in the intestinal wall associated with constipation and aging.

Ulcerative Colitis

A chronic inflammatory bowel disease affecting the mucosa and submucosa, causing bloody diarrhea and cramps.

Crohn's Disease

A chronic inflammatory condition affecting all layers of the intestinal wall, leading to pain and diarrhea.

Colorectal Cancer

The fourth most common cancer in the U.S., often screened by colonoscopy or fecal occult blood tests.