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The Digestive System 3 Functions of the Digestive System ● Digestion ○ The process by which the digestive system breaks down food into molecules that the body can use ■ Mechanical ● Foods are physically broken apart into smaller pieces (Chewing) ■ Chemical ● Chemicals produced by your body break large molecules into small ones (Enzymes) 3 Functions of the Digestive System ● Absorption ○ The process by which nutrients pass through the lining of your digestive system into your blood ■ Blood ● Transports the nutrients throughout body ● Elimination ○ Materials not absorbed are eliminated from the body as wastes Structures of the Digestive System ● ● ● ● ● ● ● ● ● Mouth Pharynx Esophagus Stomach Small Intestine Large Intestine Liver Gallbladder Pancreas Structures of the Digestive System ● Mouth ○ ○ ● Pharynx ○ ○ ● Mechanical Digestion ■ Teeth tear, crush, and grind your food ■ Tongue pushes food around Chemical Digestion ■ Enzymes in saliva begin to breakdown starches ■ Moistens food so it can be swallowed Upper portion of the throat Junction between digestive tract and respiratory system Epiglottis ○ Seals off trachea(windpipe) preventing food from entering the lungs Structures of the Digestive System ● Esophagus ○ Muscular tube that connects the pharynx to the stomach ■ Peristalsis ● Muscle contractions push food through esophagus to stomach ● Continue throughout the digestive system Structures of the Digestive System ● ● Stomach ○ Muscular pouch in the abdomen ■ Mechanical Digestion ● Layers of muscle produce churning motion ● Mixes food with fluids like a washing machine ■ Chemical Digestion ● Gastric juice containing hydrochloric acid is released ● Hydrochloric acid helps break down food ● Pepsin (enzyme) breaks down proteins and converts to amino acids ● Stomach lining is coated with mucus ● Mucus protects stomach lining from contact with hydrochloric acid ○ Peptic Ulcer - hole in stomach lining Chyme ○ Thick liquid that moves to the small intestine Structures of the Digestive System ● Small Intestine ○ ● Liver ○ ● Produces bile, a substance that physically breaks up large fat droplets that clump together Gallbladder ○ ● 20 foot long tube, where most chemical digestion and absorption of nutrients takes place Stores and releases bile into the small intestine Pancreas ○ Secretes enzymes into the small intestine ○ Enzymes break down carbohydrates, protein, and fats ○ After enzymes break down food, nutrients can be absorbed Structures of the Digestive System ● Villi ○ ○ ○ ● Millions line the small intestine Finger like projections that absorb nutrients Nutrients pass from villi to your blood, where they are transported throughout the body Large Intestine ○ ○ ○ ○ Undigested material and unabsorbed water is pushed to the large intestine 5 feet long Water is absorbed into blood Waste material is compressed and pasted to the rectum