1. The Digestive System N:

2. Function
The main function of the digestive system is to break down macromolecules into substances the body can use

3. Digestion Food provides (most of) the nutrients we need to survive
Food is processed in 4 stages:
Ingestion
Digestion
Absorption
Elimination

4. Differences in other animals...

5. Differences in other animals...

6. Differences in other animals...
Can you think of any others?

7. The digestive tract is a tube that runs from the mouth to the anus
The digestive tract is a tube that runs from the mouth to the anus. Food passes through the tract and its related organs.
The accessory organs are ones that assist in the process of digestion, food does not travel through them.

8. The digestive tract

9. In the mouth... Digestion begins in the mouth
Mechanical destruction of food
specialized, omnivorous teeth
why do we chew food?
Enzymatic breakdown of food
saliva enzymes break chemical bonds (remember the soda cracker?)

10. What does it eat?

11. What does it eat?

12. What does it eat?

13. What does it eat?

14. Through the pharynx and esophagus...
Peristalsis occurs in the esophagus and small and large intestines to move food
Peristalsis – involuntary smooth muscle contractions that force contents onward

15. To the stomach...
The human stomach contains complex gastric juices that continue the breakdown of food
These juices contain...
mucus
hydrochloric acid
enzymes

16. *Just beyond the stomach...
The “chyme” is treated by accessory organs

17. Into the small intestine...
In the small intestine (~6m long), macromolecules are digested into monomers and absorbed into the blood stream
Villi & microvilli maximize the absorptive surface area
Absorption into blood

18. The large intestine home-stretch...
Unabsorbed materials enter the large intestine (~1.5m long)
Primary roles:
House helpful bacteria
Absorb water
10 trillion bacterial cells convert undigestible nutrients into things we can use

19. Finally, the rectum & anus!
holding area for feces
absorbs a little water
Anus
sphincter that releases feces

20. Homeostasis Define the following:
Ulcer
Colon cancer
Gall stones
Cirrhosis
What is a stomach ache? What causes them?
What causes diarrhoea and constipation?