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DIGESTIVE SYSTEM

DIGESTIVE SYSTEM. FUNCTION. 4 FUNCTIONS: . 1. Physical breakdown of food into smaller pieces 2 . Change food chemically by digestive juices into the end products of fat, carbs, and protein 3 . Absorb nutrients into blood capillaries of the small intestine

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DIGESTIVE SYSTEM

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  1. DIGESTIVE SYSTEM FUNCTION

  2. 4 FUNCTIONS: 1. Physical breakdown of food into smaller pieces 2. Change food chemically by digestive juices into the end products of fat, carbs, and protein 3. Absorb nutrients into blood capillaries of the small intestine 4. Eliminate waste products of digestion

  3. LOOK ON PG 392 FIGURE 18-15

  4. DIGESTION TERMS • Bolus • Soft, pliable ball of semi-digested food • Peristalsis • Wavelike motions that move food along esophagus, stomach and intestines • Ptyalin • In saliva in mouth, converts starches to simple sugar • Chyme • Food which has undergone gastric digestion • Enzymes • Help in digestion • Chemical substances found in various digestive juices

  5. DIGESTION in the STOMACH: Gastric juices released Stomach churns and mixes food and juice (chyme) Small amounts chyme enter duodenum Takes 2-4 hours for stomach to empty

  6. DIGESTION in the SMALL INTESTINE: Digestion completed, absorption occurs Addition of enzymes from pancreas and liver (via gallbladder)

  7. DIGESTION in the LARGE INTESTINE: • Large quantities of water absorbed back into bloodstream • Bacteria help break down undigested food • Gas formation (flatulence) from bacterial action • Feces • Undigested semi-solid waste • Defecation • Colon and rectal muscles contract, external anal sphincter under conscious control

  8. MOUTH (Figure 18-14 pg. 391) • Food enters digestive system through mouth • Broken down by teeth and mixed with saliva • Inside mouth covered with mucous membrane • Roof of mouth is hard palate • Uvula • Prevents food from going up nose when you swallow

  9. TONGUE Attached to floor of mouth Helps in chewing and swallowing Made of skeletal muscle Taste buds on surface

  10. SALIVARY GLANDS • Three pairs • What are they? • Parotid: secretes ptyalin salivary amylase onto inner cheeks • Submandibular: secretes mucin and ptyalin at base of tongue • Sublingual: secretes mucous (no ptyalin) and found on either sides of tongue • Smallest of the three • Secrete saliva • Parotid • Largest salivary glands, become inflamed during mumps

  11. TEETH • Gingiva – gums that support and protect teeth • Mastication – chewing • Deciduous – baby teeth • How many? • Adult teeth • How many?

  12. STOMACH • Cardiac sphincter • Circular layer of muscle • Controls passage of food into stomach • Pyloric sphincter • Regulates entrance of food into duodenum • Rugae • Mucous coat lining • Folds when stomach empty • Muscular coat contracts (peristalsis) to push food into small intestine

  13. SMALL INTESTINE • Three sections: • What are they? Look on pg. 385 • Absorption • Digested food (nutrients) pass into bloodstream and on to body cells • Undigestablepasses on to large intestine • Read “Did you know?”

  14. SMALL INTESTINE continued END PRODUCTS OF DIGESTION: Carbohydrates are converted to simple sugars such as glucose Proteins are broken down into amino acids Fats are changed into fatty acids and glycerol

  15. PANCREAS and GALLBLADDER • Pancreas • Exocrine function – secretes digestive enzymes • Also has endocrine function • Gallbladder • Stores bile • When fatty foods digested, bile released by gallbladder

  16. LIVER Manufactures bile Produces and stores glucose in the form of glycogen Detoxifies alcohol, drugs and other harmful substances Manufactures blood proteins Stores vitamin A, D and B complex

  17. LARGE INTESTINE Water absorption Bacterial action Fecal formation Gas formation Defecation Look on pg. 393 and WRITE DOWN a few notes on each

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