1. Digestive System

2. Digestive System
a coiled, muscular tube (6-9 meters long) beginning with the mouth and ending with the anus
The main role of the digestive system is to break down and absorb nutrients that are necessary for growth and maintenance.

3. The Path of Digestion Mouth Esophagus Stomach Small intestine
Large intestine
Rectum
Helpers are: liver, gall bladder & pancreas

4. process by which food is converted into soluble forms
Digestion
process by which food is converted into soluble forms
2 forms of digestion
physical or mechanical
chemical

5. Forms of Digestion Physical Digestion Chemical Digestion
 mechanical breakdown of food into smaller particles
 chemical breakdown of food by enzymes
 begins in mouth by chewing – teeth and tongue
 begins in mouth with saliva
 increases surface area of food
 mostly occurs in small intestine

6. Physical Digestion Chemical Digestion
 mechanical
 chemical
 begins in mouth by chewing
 begins in mouth with saliva

7. Stages of Digestion      movement propels food through system
secretion
release of digestive juices 
digestion
breakdown of food into molecular sizes
food molecules passing through intestinal walls 
absorption
elimination 
removal of undigested food

8. Primary Digestive Organs

9. begin the mechanical breakdown of food
teeth
mouth
tongue
- transports food to stomach through the process of peristalsis
esophagus
- muscular organ that stores, mixes, digests and controls passage of food
stomach

10. Esophagus Moves food from the back of throat to the stomach
Epiglottis – flap of skin that covers windpipe (trachea), keeping food out of lungs
Valve at the end of the esophagus (sphincter) allows food to pass into the stomach but not back into the esophagus
Takes about 8-10 seconds to move bolus (chewed food) from swallowing to stomach

11. Peristalsis
series of involuntary muscular contractions in the esophagus that squeeze the food down to the stomach
esophagus
food
stomach

12. From the esophagus to the Stomach
Click on picture to show video

13. Stomach
Muscular walls of stomach contract to churn and mix the food with gastric juices
Gastric juices (hydrochloric acid and pepsin with mucus) - begin the break down of proteins
Chemical and mechanical digestion takes about 2 to 3 hours
Mixture of partially digested food is called chyme

14. - coiled tube from 3 - 6m long, the major site for digestion and absorption of nutrients; contain villi
small intestines
m long tube, absorbs water from undigested material
large intestines
- opening for removal of feces
anus

15. Small Intestine Chyme is flooded with enzymes
Enzymes help break down the nutrients to basic forms
Liver produces bile (stored in the gall bladder) – a salt that helps break down fats
Villi - finger like projections in the wall of the small intestines where blood vessels absorb nutrients into the bloodstream

16. Large Intestine
Undigested material (fiber, water, and un-digestible substances) moves into the large intestine or colon
Water is removed and undigested material reduced to a solid waste called feces
Colon contains bacteria to help final digestion
Feces (yes, poop) is stored in the rectum and eliminated

17. Elimination
Undigested waste is moved into the rectum where it is eliminated through the anus
Peristalsis – the muscular contractions that move food through your digestive system

18. Accessory Digestive Organs

19. salivary glands
- secrete a chemical (enzyme) that breaks down starch into glucose
liver
- produces bile, which helps break down fats in small intestines
gall bladder
- stores bile
pancreas
- secretes enzymes that break down starches and proteins

20. The Liver (& Gall Bladder)
Liver produces bile to help with chemical digestion
Bile stored in the gall bladder (then sent to beginning of small intestine)
The liver filters harmful substances or wastes, turning some of the waste into more bile
The liver helps figure out how many nutrients will go to the rest of the body, and how many will stay behind in storage.
For example, the liver stores certain vitamins and a type of sugar your body uses for energy.

21. Accessory Digestive Organs connected to stomach by ducts
liver
gall bladder
pancreas

22. Pancreas
Produces some digestive enzymes

23. Digestive Disorders

24. spot in stomach lining where cells are destroyed, lining unprotected, irritated by stomach acid
ulcers
gastritis
swelling of stomach lining, caused by irritating foods, alcohol, or bacteria
acid reflux
"back washing" of acid from the stomach into the esophagus; also called heartburn

25. Chemical Digestion
Mouth - chemical digestion begins in the mouth with saliva (spit)
Stomach - gastric juices (stomach acid, mucus, enzymes) begin to break down the food to smaller molecules
Small intestine – food broken down even more so your body can absorb the nutrients
** Most digestion occurs in the small intestine – fats, proteins, and carbs.
Large intestine – bacteria help with final stage of digestion

26. Nutrients Carbohydrates: starches and sugars
Proteins: simplest form is amino acids
Fats : absorbed as fatty acids (with the help of bile from the liver)
Vitamins & Minerals
Water

27. Enzymes Enzymes are proteins that help chemical digestion
Enzymes help a chemical reaction without being changed itself
Found in raw fruits and vegetables
Also produced in the stomach, small intestine and pancreas

28. Review

29. 1. 2. 3. 4. 5. 6. 7. 8. 9.
10.

30. 1. mouth 1.
2. esophagus 2. 3.
3. stomach 4.
4. small intestine 5.
5. large intestine
6. anus 6.

31. salivary glands 1.
liver 2.
gall bladder 3.
pancreas 4.

32. 1. 2. 3. 4. 5. 6.

33. 1. 2. 3. 4.

34. Match the structure with the number.  
liver
small intestine
salivary glands
pancreas
large intestine
gall bladder
esophagus
stomach
anus      

35.          Match the function with the number.
major organ for digestion and absorption of nutrients
contains enzymes for the first chemical breakdown of food 
transports food by peristalsis
stores undigestible food
secretes enzymes for starch breakdown
mixes and stores food
the 4 accessory digestive organs
stores bile
produces bile
contains villi      