Digestive System

Functions

Ingestion Food enters digestive tract through mouth

Mechanical Processing Physical manipulation of solid food (by t0ngue and teeth)

Digestive Chemical breakdown of food into small organic fragments that can

be absorbed by the digestive epitheliumSecretion

Release of water, acids, enzymes, and buffers by the digestive tract and accessory organs

Absorption Movement of molecules (organic, water, electrolytes, vitamins)

across the digestive epithelium and into the interstitial fluid of the digestive tract

Excretion Removal of waste products from the body (feces)

Structures

Oral cavity, Teeth, Tongue Mechanical processing Moistening Mixing with salivary secretions

Salivary Glands Secretion of lubricating fluid containing enzymes that

break down carbohydratesPharynx

Muscular propulsion of materials into the esophagusEsophagus

Transport of materials to the stomach (peristalsis)

Structures

Stomach Chemical breakdown of materials by acid and enzymes Mechanical processing through muscular contractions

Liver Secretion of bile

Important for lipid digestion Storage of nutrients

Gallbladder Storage and concentration of bile

Pancreas Exocrine cells secrete buffers and digestive enzymes Endocrine cells secrete hormones

Structures

Small Intestine Enzymatic digestion and absorption of water, organic

substrates, vitamins and ionsLarge Intestine

Dehydration and compaction of undigestible materials in preparation for elimination

Anus