Human Biology Notes
BIO 202
Chapter 16: The Digestive System
SECTION 16.1: DIGESTION BEGINS IN THE ORAL CAVITY
● THE DIGESTIVE SYSTEM HAS TWO MAJOR PARTS
○ The GASTROINTESTINAL SYSTEM OR GI TRACT
■ The GI TRACT BEGINS AT THE ORAL CAVITY AND ENDS AT THE
ANUS
○ A SET OF ACCESSORY ORGANS INCLUDE THE PANCREAS, LIVER, AND
GALLBLADDER
● The GI TRACT AND ACCESSORY ORGANS CARRY OUT FIVE BASIC PROCESSES
○ Ingestion: FOODS AND LIQUIDS ARE TAKEN INTO THE MOUTH AND EATEN
○ Mixing: THE SMOOTH MUSCLE IN THE WALLS OF THE GI TRACT MIXES
THE FOOD WITH DIGESTIVE ENZYMES
○ Digestion: FOOD IS BROKEN DOWN BY BOTH MECHANICAL AND
CHEMICAL PROCESSES
, ○ Absorption: THE EPITHELIAL CELLS LINING THE GI TRACT ABSORB
THE GI TRACT STRUCTURE
BIO 202
Chapter 16: The Digestive System
SECTION 16.1: DIGESTION BEGINS IN THE ORAL CAVITY
● THE DIGESTIVE SYSTEM HAS TWO MAJOR PARTS
○ The GASTROINTESTINAL SYSTEM OR GI TRACT
■ The GI TRACT BEGINS AT THE ORAL CAVITY AND ENDS AT THE
ANUS
○ A SET OF ACCESSORY ORGANS INCLUDE THE PANCREAS, LIVER, AND
GALLBLADDER
● The GI TRACT AND ACCESSORY ORGANS CARRY OUT FIVE BASIC PROCESSES
○ Ingestion: FOODS AND LIQUIDS ARE TAKEN INTO THE MOUTH AND EATEN
○ Mixing: THE SMOOTH MUSCLE IN THE WALLS OF THE GI TRACT MIXES
THE FOOD WITH DIGESTIVE ENZYMES
○ Digestion: FOOD IS BROKEN DOWN BY BOTH MECHANICAL AND
CHEMICAL PROCESSES
, ○ Absorption: THE EPITHELIAL CELLS LINING THE GI TRACT ABSORB
THE GI TRACT STRUCTURE
