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Download The Digestive System Three (3) main functions Breaks down food
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The Digestive System Three (3) main functions Breaks down food Into molecules body can use Molecules absorbed into blood Carried throughout body Wastes are eliminated Digestion Mechanical digestion Physically broken down Chewing, grinding Chemical digestion Chemicals produced by body Mix with food, change it chemically Example: starch changes into sugar molecules Absorption Nutrients pass into blood Transported to all cells in body Elimination Materials not absorbed Fiber is an example Put out of body as waste Parts of the digestive system Mouth Mechanical digestion in mouth Teeth cut and grind food Incisors cut Canines tear and slash Molars grind Chemical digestion Saliva mixes with food as teeth work Changes starch into sugar molecules An enzyme in saliva caused this to happen Enzyme - protein that speeds up chemical reactions Esophagus Muscular tube - connects mouth to stomach Lined with mucus - makes food easier to swallow Smooth muscles push food toward the stomach Muscular waves are called peristalsis Keep food moving toward stomach Epiglottis - seals off windpipe when you swallow Stomach Mechanical digestion in the stomach Most mechanical digestion occurs here Churns and mixes food Like a washing machine mixes soap and clothes Chemical digestion in the stomach Digestive juices mix with food Enzymes like pepsin digest proteins Breaks proteins into amino acid pieces Hydrochloric acid helps pepsin work Kills many bacteria swallowed with food Stomach lining Protects stomach with thick coat of mucus Food remains in stomach until all solid material is broken down Thick liquid is then released into small intestine Small Intestine Almost all chemical digestion takes place here Almost all absorption of nutrients takes place here Name for small diameter Actually about 6 meters long Starch, proteins already partially broken down Fats have not been broken down at all Enzymes and secretions are mixed here Produced by pancreas, liver, small intestine Liver Largest organ inside the body Extremely busy chemical factory Plays a role in many body processes Produces BILE to aid digestion Bile breaks large fat particles into smaller droplets Pancreas Produces enzymes that break down starches, protein, fats Produces insulin Villi Tiny, finger-shaped structures inside small intestine Nutrient molecules pass into blood vessels here Greatly increase surface area in small intestine Large Intestine Last section of digestive system About 1.5 meters long Bacteria here help make certain vitamins Water removed here Remaining material is readied for elimination Rectum Waste material compressed into solid form Eliminated from the body through the anus Muscular opening at end of rectum
