1. Chapter 30.3: The Digestive System

2. Functions of the Digestive System
Ingestion
Take food into body
Digestion
Mechanical
Physical breakdown of food into small pieces
Chemical
Enzymes break down food into individual nutrients
Absorption
Nutrients absorbed into body
Elimination
Waste is compacted and eliminated

3. The Mouth - Teeth Saliva Tongue Pharynx
Incisors, cuspids, and bicuspids cut and tear food
Molars grind food
Saliva
Amylase breaks down starch
Tongue
Forms a bolus, or ball of food
Pushes food into back of throat, or pharynx
Pharynx
Contains epiglottis, which blocks the trachea and prevents choking

4. The Esophagus Connects the pharynx to the stomach
Moves food by peristalsis
Smooth, wave-like muscle contractions

6. The Stomach
Is a muscular sac that continues mechanical and chemical digestion
Chemical digestion
Protein is broken down by the enzyme pepsin
Hydrochloric acid (HCl) also breaks down food
Mechanical digestion
Stomach squeezes and churns food to produce chime
Chyme is the mixture of food and digestive enzymes

7. The Small Intestine Begins at stomach and ends at large intestine
First section called the duodenum
Chemical digestion by enzymes continues after food is pushed from stomach
Enzymes are made in the small intestine walls, or from the pancreas

9. The Small Intestine
Absorption of nutrients into the blood occurs through villi
Villi are fingerlike projections that line the small intestine, and are covered with microvilli
Microvilli are tiny projections of cells on villi that aid nutrient absorption

11. The Pancreas Connects to the small intestine by a duct
Makes and secretes sodium bicarbonate, which neutralizes stomach acid
Makes and secretes enzymes, which break down food
Also produces hormones that regulate blood sugar

12. The Liver and Gallbladder
Liver produces bile
Gallbladder stores bile, and secretes it by a duct into the small intestine
Bile helps break down fats

13. The Large Intestine Also called the colon
Connects to the small intestine and ends at the rectum
Absorbs water from chyme
Supports colonies of bacteria
Compacts unused nutrients into solid waste

15. The Rectum and Anus
Elimination occurs after the large intestine has compacted solid waste into feces
Feces is stored in the rectum
Anus is the muscle that controls release of feces