Nutrition course for nursing students

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- Break 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. 

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

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

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

24. Intestinal Wall Cells

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

26. Thank