1. http://www.lifedynamix.com/articles/files/iStockKidNutrition.jpg

4. Us! http://www.mennellmedia.co.uk/Biology%20-%20Organisms.html

5. Digestive System overview:

6. Functions of the digestive system Ingestion Mechanical processing Digestion Secretion Absorption Excretion http://www.mydr.com.au/default.asp?Section=gastrointestinalhealth http://greenfield.fortunecity.com/rattler/46/upali4.htm

7. The Digestive process can be broken down into 4 parts: 1.Ingestion – taking in of nutrients 2.Digestion – breakdown of complex molecules into smaller components by enzymes 3.Absorption- transport of digested nutrients to the tissue of the body 4.Excretion – removal of waste food material from the body

8. Animation The digestive system

9. Part 1-Ingestion: eating Physical digestion begins in the mouth, where food is chewed and formed into a bolus (greek word for ball) by the tongue.

10. In the mouth: physical and chemical digestion starts! Teeth: physical breakdown of food into smaller pieces. Saliva: chemical breakdown of starch into simple sugars (enzyme Amylase), lubricates food so it can be swallowed and makes food taste…good or bad

11. Teeth…a comparison

12. Saliva: Contains the enzyme AMYLASE that breaks down starch into simple sugars Lubricates food Dissolves food particles Activates the taste buds

14. Part 2-Digestion is beginning……. The bolus goes through the pharynx, closes the epiglottis (so food doesn’t enter the trachea) and enters the esophagus…

15. Food and fluids move through the esophagus NOT because of gravity but because peristalsis. Peristalsis = rhythmic, wavelike muscle contractions http://www.walgreens.com/adamHtml/animation/200000.htm Esophagus

16. Peristalsis is why we can drink while standing on our head!

17. Sphincters Is a ring-shaped muscle that relaxes or tightens to open or close a passage or opening in the body. Examples are the anal sphincter (around the opening of the anus) and the pyloric sphincter (at the lower opening of the stomach).

18. There is a sphincter at the top and the bottom of the esophagus.

19. “do not try this at home”!!

20. So, the food has now passed through the esophagus, thru the lower esophageal sphincter and into the stomach…

21. Bulk storage (capacity of approx 1.5L) of undigested food Mechanical breakdown of food (muscular contractions of the stomach) Disruption of chemical bonds via acids and enzymes Functions of the stomach

22. Structure of stomach Millions of cells line the inner wall of the stomach These cells secrete gastric fluids

23. 1.Mucus: protects stomach against digestion and corrosion 2.HCl: hydrochloric acid kills harmful substances ingested with food 3.Pepsinogen: is activated to pepsin in the presence of HCl, the enzyme pepsin digests protein Gastric Juices:

24. Problems: ulcers and heartburn http://www.walgreens.com/adamHtml/animation/200000.htm

25. Endoscopy:

26. So far, chemical digestion PartEnzymeDigestsExample MouthAmylaseCarbsBread StomachPepsinProteinsMeat HCl (hydrochloric acid) allows pepsin to do its digestion and kills pathogens that come into the stomach.

27. Mechanical digestion MouthTeeth StomachMuscular contractions Physically breaking food into smaller pieces so there is more surface area for chemical digestion.

28. Labelling Label the diagram of the digestive system

30. Next stop on the digestive bus: thru the pyloric sphincter to the small intestine… Just something to look forward to……