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Digestion, Absorption and Metabolism

Digestion, Absorption and Metabolism. Presented by Janice Hermann, PhD, RD/LD OCES Adult and Older Adult Nutrition Specialist. What Is Digestion. Process whereby the body breaks down food into absorbable nutrients. Digestive tract is a long tube surrounded by muscles.

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Digestion, Absorption and Metabolism

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  1. Digestion, Absorption and Metabolism Presented by Janice Hermann, PhD, RD/LD OCES Adult and Older Adult Nutrition Specialist

  2. What Is Digestion • Process whereby the body breaks down food into absorbable nutrients. • Digestive tract is a long tube surrounded by muscles. • The muscles alternate contracting and relaxing pushing food along.

  3. Mouth • Teeth grind food to reduce the size. • Saliva released to help moisten food. • Some carbohydrate digestion begins. • Tongue pushes food to the back of the mouth to start swallowing reflex. • Food passes through the esophagus and enters stomach.

  4. Stomach • Distended pouch. Strong circular muscles at each end control food entering and leaving. • Mixes food by muscular contractions causing food to break up further. • Secretes hydrochloric acid: • Begins protein digestion. • Kills microorganisms in food. • Nutrients not absorbed except water and alcohol.

  5. Small Intestine • Most digestion and absorption occurs in small intestine. • Bile released to emulsify (break up) fat. • Pancreatic enzymes released to digest carbohydrates, proteins and fats. • Final digestive enzymes in intestinal lining break down carbohydrates, proteins and fats into absorbable units.

  6. Final Digestion Products • Final digestion products absorbed by cells lining small intestine. • Carbohydrates: • Monosaccharides • Proteins: • Amino acids • Chains of 2 or 3 amino acids • Fats: • Fatty acids • Glycerol • Monoglycerides • Vitamins, minerals, water and some larger fat-like compounds such as cholesterol are not broken down before they are absorbed.

  7. Absorption • Water-soluble nutrients and short fatty acids released directly into the bloodstream. • Longer fatty acids, fat-soluble vitamins, and fat-like compounds such as cholesterol are not water-soluble. • Triglycerides reform in intestinal wall. • Packaged into a chylomicron and released into lymphatic system.

  8. Indigestible Matter • After digestion and absorption of nutrients, indigestible matter, such as fiber moves into the large intestine. • Indigestible matter is compacted by removing water. • Little nutrient absorption occurs in large intestine.

  9. Metabolism • Chemical reactions that occur in the body: • Building and maintaining body tissues • Regulating body functions • Supplying energy • For metabolism to occur the body needs: • Water • Energy • Oxygen • Nutrients

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