1. The Digestive System
From Food to Nutrients

2. The Digestive System - Purpose
The function of the digestive system is to break down food into small molecules which can diffuse into the blood stream where they can be delivered to all cells of the body to use for energy, cell activities, cell parts, making enzymes, growth, repair, and body defenses.

3. Overview of System The Digestive Tube: Accessory Organs
Food actually passes through these organs:
Mouth
Pharynx
Esophagus
Stomach
Small Intestine
Large Intestine
Rectum
Anus
Accessory Organs
These organs produce chemicals that help with digestion:
Salivary Glands
Liver
Gall Bladder
Pancreas

4. Two Kinds of Digestion Physical Digestion:
Food is broken into smaller PIECES
Chemical Digestion: Food is broken into smaller molecules.

5. From Food to Nutrients – Pizza!

6. The Mouth –includes teeth & tongue
Teeth break food into smaller pieces
Saliva is secreted into the mouth from the salivary glands to help lubricate the food
Tongue forms a bolus (ball) of food that can be swallowed easily
Amylase begins some
digestion of starch

7. The Pharynx – Don’t Choke!
Part of both digestive and respiratory system
When swallowing, a small flap called the epiglottis blocks the opening of your windpipe
Allows food to go down the esophagus
“Down the wrong tube”

8. The Esophagus 10 inch long, muscular tube
Transports food from mouth to stomach
Food doesn’t just slide down, muscles contract to push the food
down – peristalsis
2-3 seconds to go down

9. The Stomach Stretchy, J-shaped sac Stomach is like a blender
Slowly grinds food into mush
called chyme
Pepsin (proteinase) breaks
down proteins into amino acids
Acids denature bacteria

10. Small Intestine – First half!
1 inch in diameter, 21 ft long (stretched out)
Food spends about 4 hours in the S.I.
Bile (from liver) breaks fats into smaller pieces.
Bicarbonate (from pancreas)
neutralizes stomach acid.
Lipases, starchases, and
proteinases from small intestine
and pancreas digest food.

11. Small Intestine – second half! Absorption
By now, the food is
digested into small and
medium molecules.
LOTS of thin finger shaped
projections called villi line
the small intestine.
Nutrients diffuse through
the villi into the blood stream
and travel to your cells.

12. Surface are to volume ratio!!!!!!

13. The Appendix
Tiny tube with closed end coming off the L.I.

14. The Large Intestine 2-3 inches thick 5-6 feet long
Undigested food and water passes through
Absorbs water as waste passes through forming feces (solid waste)

15. The Last Stop: Rectum & Anus
5 inch, muscular sac
Waste is solidified
Storage for feces.
Anus
Ring shaped muscle
Releases feces

16. The Liver and the Gallbladder
Liver is the largest organ – small football
Produces bile which changes large fat drops into smaller droplets.
Gallbladder – small 1 inch sac behind liver
Stores bile from liver
Bile secreted into the
small intestine as needed

17. The Pancreas 6 inches long – spongy – behind stomach Secretes:
Bicarbonate to neutralize stomach acid
Proteinases to digest protein
Starchases to digest starches
Lipases to digest fats

18. Very Important!
The digestive system is very important because without it, your body couldn’t get the nutrients it needs in order to grow big and strong!