1. Digestive System

2. Digestive system’s role is to break down ingested food into molecules that are small enough to be absorbed by the body.
Eliminate solid waste

3. Anatomy of the Digestive System
Remember: Organs of the digestive tract are
Divided into two groups
Part I: Digestive Tract (6 parts)
1. Mouth 2. Pharynx
3. Esophagus 4. Stomach
5. Small Intestine 6. Large Intestine
Digestive tract: mouth to anus, tube 4 to 6 m in length
surrounded by muscles –crush food and
move it along

4. Part II: Digestive Glands (secrete substances) 1. Salivary Glands
2. Liver
3. Pancreas
4. Gastric Glands
5. Intestinal Glands
Digestive Glands: secrete substances that aid in the digestion of food (found either in the digestive tract or attached to it).

5. Processing Food Ingestion and propulsion of food Digestion of food
Absorption of nutrients
Elimination of fecal matter

6. Ingestion: act of taking substances into the body through the mouth. Ex. Food etc.
Two mechanisms:
Deglutition: swallowing the food
Peristalsis: muscular contractions of the esophagus, stomach, small intestine, and large intestine which move substances through the digestive tract.

7. Deglutition (Swallowing):
1. Epiglottis closes the trachea
2. Uvula closes the nasal cavity
3. Food travels without getting into the
respiratory tract

10. Digestion
The transformation of food into nutrients that can be used by the body.
Two types:
1. Mechanical transformation consists of
physically breaking down food into smaller
substances in preparation for chemical
transformation
a) Chewing: crushing & grinding
(teeth, muscles of mouth)
b) Churning: muscle contractions mix food with
digestive secretions (stomach, SI)

11. 2. Chemical transformation: breaks down the complex molecules of food into simpler molecules. These changes occur with the help of secretions from the digestive glands.
Remember: Nutrients are foods that can be absorbed by the body
Copy Table 6.15 p. 170 into your notes!

13. Digestion of Proteins, Carbohydrates, and Fats

14. 2. Carbohydrates

15. 3. Fats

17. Absorption of Nutrients
Passage of nutrients from the digestive tract into the blood or lymph
Most food absorbed in small intestine
Folds called villi increase surface area for absorption (in lining contains blood and lymph vessels)

19. Elimination of Fecal Matter
Large Intestine:
1. Residue - contains little nutrient matter
- arrives in liquid form
2. Water in residue gradually absorbed.
3. By rectum, very little water left (feces solid)
4. Feces expelled through anus

22. l
Copy 6.18 p. 172 see worksheet