Digestion, Absorption, and Metabolism

Nutrition course for nursing students

1. NUTRITION (4)

2. Digestion, Absorption, and Metabolism Introduction: Nutrients released from food remain unavailable to the body until they cross the intestinal wall and enter the circulatory system for transport to tissues

3. Objectives - Describe the processes of digestion, absorption, and metabolism. - Name the organs in the digestive system and describe their functions.

4. - Name the enzymes or digestive juices secreted by each organ and gland in the digestive system .

5. Digestive System GI tract (alimentary canal) composed of :- 1. Mouth 2. esophagus 3. Stomach 4. small intestine 5. large intestine 6. rectum

6. Accessory organs of GI: a- Pancreas b- Gallbladder c- Liver

7. Digestive System

8. Functions of the GI Tract : 1- Receives Food 2- Releases nutrients from food 3- Delivers nutrients into the blood 4- Excretes indigestible foods (waste)

9. Digestion ( الهضم ) Is the breakdown of food into smaller components that can be more easily absorbed and assimilated by the body.

10. Digestion is divided in to two: a - Mechanical digestion: Means food is broken into smaller pieces by teeth and along the gastrointestinal tract by peristalsis.

11. b - Chemical digestion: Means foods are broken down into nutrients by using hydrolysis and Enzymes.

12. Function of mouth in digestion: 1- Produce enzyme (salivary) acts on starch. 2- B reak up food and mixes with saliva. 3- Bolus formed . 4- Sensations of taste

13. Function of esophagus in digestion: a- Travels food to the stomach b- Connects mouth to stomach

14. Function of stomach in digestion: 1- Temporary storage of food 2- Mixing the food with gastric juices 3- Emptying of food into the intestine

15. 4- Destruction of most bacteria that were accidentally consumed. 5- Secretes acid – pH, Mucus (helps to move food along GI tract and protects stomach lining) 6- And secretes enzymes primarily pepsin, (which breaks down protein)

16. Function of small intestine in digestion: a- Performs the major role of chemical digestion b- Secretions enzymes, mucus, hormones

17. c- Prepares foods for absorption d- Produces enzymes (lactase, maltase, sucrase convert lactose, maltose, sucrose to simple sugars ).

18. e- Peptidases reduce proteins to amino acids. f- Most of absorption takes place in the small intestine

19. Large Intestine Major function of the large intestine are: 1- Absorb water 2- Synthesize some B vitamins and vitamin K 3- Collect food residue

20. Absorption ( امتصاص ) Define as the passage of nutrients into the blood or lymphatic system .

21. Nutrients must be in their simplest form to absorbed: Carbohydrates: simple sugars (glucose) Proteins: amino acids Fats: fatty acids and glycerol

22. - Most absorption occurs in the small intestine - Water is absorbed in the stomach, small intestine, and large intestine.

23. Intestinal Wall Cells

24. Metabolism ( الأيض ) - Define as the transformation of nutrients into energy within the cell. - Occurs after digestion and absorption

25. Thank