The digestive system breaks down food, absorbs nutrients, and eliminates waste. It consists of the mouth, esophagus, stomach, liver, pancreas, small intestine, large intestine, and rectum. The mouth breaks down food, the esophagus transports it to the stomach for further breakdown and nutrient absorption. The stomach, liver, pancreas, and small intestine aid in digestion and absorption of nutrients. The large intestine absorbs water and forms waste before it is eliminated by the rectum and anus. Proper digestion involves both mechanical and chemical breakdown of food by these organs over varying time periods as it passes through the system.

1. Functions of Digestive
System
• Breaks down food into smaller
portions
• Absorbs nutrients into the
bloodstream and transfers nutrients
to the cells to produce energy.
• Aids in the elimination process of
undigested food.

2. Parts of the Digestive System
• Mouth
• Organs
* Esophagus
* Stomach
* Liver
* Pancreas
* Small intestine
* Large intestine
* Rectum
* Anus

3. Esophagus
• A long and muscular tube that connects
the pharynx to the throat to the
stomach.
• The wall of the esophagus is lined with
smooth muscles that contract
rhythmically to move the food through
the digestive system in the process called
peristalsis.

4. Stomach
• The large J-shaped organ at the end of
the esophagus, on the left side of the
body. The capacity of the stomach is 50
mL when empty and can expand up to 2
to 4 liters when full.
• The end of the stomach has a
sphincter muscle that closes and
opens to allow the flow of food from the
esophagus to the stomach.

5. Liver
Largest gland in the body. It
secretes bile that helps digest
fats. The bile is stored in a small
pouch called gallbladder.
Bile has substances that aid in
the digestion of fats and lipids.

6. Pancreas
Produces pancreatic juices that
neutralize the acidic stomach
content before they are moved
into the small intestine. The
pancreas also secretes lipase,
an enzyme that breaks fat
molecules.

7. Small Intestine
• Narrow coiled tube connected to the
stomach. If it stretched it is about 7
meters long.
• Three parts: duodenum, jejunum, and
ileum.
• Has villi, small finger-like projections that
protrude in the lining of intestinal wall. It
increase the internal surface of the
intestinal wall to increase the absorptive
area.

8. Large Intestine
• The large intestine or colon is a large
coiled tube attached to the end of the
small intestine. It is only about 1.5
meters long, which includes the colon,
rectum, and appendix and twice as
wide as the small intestine.
• The last 20 or 30 centimeters of the
colon is called rectum.

9. Parts and
functions of
the Digestive
System

10. Mouth
•Breaks up food
particles.
•Assists in producing
spoken language.

11. Salivary Glands
•Saliva moistens and
lubricates food.
•Amylase digests
polysaccharides.

12. Pharynx
swallows
Esophagus
transports

13. Stomach
• Stores and churns food.
• Pepsin digests protein.
• Hydrochloric acid activates
enzymes, breaks up food, and
kills germs.
• Mucus protects stomach wall.
• Limited absorption

14. Liver
• Breaks down and builds up many
biological molecules.
• Stores vitamins and iron.
• Destroys old blood cells
• Destroys poisons
• Bile aids in digestion
Gallbladder
Stores and concentrates bile

15. Pancreas
• Hormones regulate blood glucose
levels.
• Bicarbonate neutralize stomach acid.
• Trypsin and chymotrypsin digest
proteins.
• Amylase digests polysaccharides.

16. Small Intestine
• Complete digestion
• Mucus protects gut wall.
• Absorbs nutrients, most water
• Peptidase digests proteins.
• Sucrose digest sugars.
• Amylase digests polysaccharides.

17. Large Intestine
• Reabsorbs some water.
• Forms and stores feces.
Rectum
• Stores and expels feces
Anus
Opening for elimination of
feces

18. Digestive Process
• Mechanical Phase of Digestion
Breaking of food by means of
cutting tearing, grinding, and smashing
of food into very fine mixture.
• Chemical Phase of Digestion
Involves breakdown of large
molecules in food into smaller
substances by enzymes.

19. Structure Primary Function
Time
Food/Material
Stayed
Mouth
Mechanical and
chemical digestion
5 to 30 seconds
Esophagus Transport 10 seconds
Stomach
Mechanical and
chemical digestion
2 to 3 hours
Small intestine
Mechanical and
chemical digestion
3 to 4 hours
Large intestine Water Absorption 18 to 24 hours
Colon Waste Storage 1 to 2 days

20. Good Eating Habits
• Relax while eating your meals. Avoid
talking while eating to prevent from
choking.
• Never talk about unpleasant experience
while eating. These may cause indigestion.
• Eat a the right time.
• Chew your food slowly and properly.
• Lessen you intake of sweets.
• Take plenty of juices and water everyday.