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Digestive System. Digestive System. I. Digestion – the process that breaks food into small molecules so they can be absorbed or taken into body cells. Mechanical digestion Food chewed and mixed in mouth . Food churned in stomach . Food acted on by bile. Digestive System.
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Digestive System I. Digestion – the process that breaks food into small molecules so they can be absorbed or taken into body cells. • Mechanical digestion • Food chewed and mixed in mouth. • Food churned in stomach. • Food acted on by bile.
Digestive System B. Chemical digestions • Breaks down large molecules to smaller. • In mouth , stomach, small intestines 3. Enzymes • Proteins vital for chemical digestion • Enters a reaction and helps to join or break up into substances • Are not changed themselves • Can speed up reactions
Digestive System II. Digestion in mouth Diagram of the mouth • Mechanical digestion by tongue and teeth • Chemical digestion • Saliva • Produced by the 3 sets of salivary glands • Mostly water, but also contains mucus and enzymes (amylase) • Amylase starts breakdown of starch to sugar.
Digestive System C. Esophagus Esophagus Diagram • Muscular tube • 25 cm. long • No digestion • Peristalsis- waves of contractions that move food • Takes about 4 to 8 seconds • Peristalsis found throughout digestive systems
Digestive System III. Digestion in the Stomach Diagram of the stomach • A muscular bag with folds on the inside • Mechanical digestion done by walls of stomach and peristalsis. Real view
Digestive System C. Chemical digestion Inside the stomach • Hydrochloric acid • Enzymes work on protein • Mucus • Lubricates food, making it slick • Protects stomach lining from strong digestive juices D. Food in stomach about 4 hours E. Food changed to chyme - thin , watery liquid
Digestive System IV. Digestion in the small intestine Small intestines Diagram • Small in diameter, but about 6-7 M long • - first part of the duodenum small intestine • Major part of all digestion • Receive digestive juices from outside the digestive tract • Bile • From the liver • Greenish color
Digestive System Small intestines continue Diagram of gallbladder 3. Store in small sac : the gall bladder 4. Breaks fat molecules into smaller pieces (like detergent acts on grease) b. Pancreas • Produces insulin - helps body use sugar and other carbohydrates • Produces enzymes that break down carbohydrates, fats, proteins still further
Digestive System C. Walls of small intestine • Many ridges and folds • Folds covered with villi • Tiny, finger like projections • Make surface area larger so there are more places for to be absorbed.
Digestive System D. Chyme is now a soup of Molecules ready to be absorbed through cells on surface of villi. Capillaries around the villus • Molecules of nutrients pass by diffusion and osmosis or by active transport into blood vessels of each villus. • Remaining materials are moved into large intestines by peristalsis.
Digestive System V. Absorption in large intestine Large intestines • Main job: absorb water from the thin mixture (chyme) • Homeostasis is maintained. • Peristalsis slows down some. • Chyme may stay in large intestine for 3 days • Water and sodium are absorbed.
Digestive System D. Remaining materials • Undigested cellulose • Bacteria • Feed on undigested matter • Produce vitamins. • This is an example of a symbiotic relationship.
Digestive System E. Release of solidified wastes • Controlled by muscles in the rectum and anus. • Release in the form of feces.
Digestive System Remember Colon: Food is processed in your digestive system for the purpose of supplying your body with raw materials for metabolism. These raw materials are in the form of nutrients.
