1. The Digestive System
Chapter 15

2. Section 15.1
Functions:
Mechanical and chemical breakdown of food
Absorption of nutrients
Excretion of wastes
*Consists of alimentary canal and accessory organs

3. Alimentary Canal
Pathway by which food enters the body and solid wastes are expelled
Includes:
Mouth
Pharynx
Esophagus
Stomach
Small intestine
Large intestine
Anus

4. Wall of the Alimentary Canal

5. Section 15.2 Layers of the Canal
1.  Mucosa - protects tissues and carries out absorption
2.  Submucosa - glands, blood vessels, nerves
3.  Muscular Layer - smooth muscle tissue, pushes food  (PERISTALSIS)
4.  Serosa (serous layer) - outer covering of the tube, lubricates surfaces (serous fluid)

7. Mixing Movements
Contractions mix food with digestive juices
Peristalsis - pushes food down the tube

8. Anatomy of the Mouth

9. Teeth
 -responsible for mechanical breakdown of food

10. Submandibular - below jaw Sublingual - under tongue
Salivary Glands
Parotid - ear, cheek
Submandibular - below jaw
Sublingual - under tongue
AMYLASE – enzyme in saliva that breaks down starch
*Food begins to turn into a BOLUS

11. Pharynx 
nasopharynx
oropharynx
hypopharynx

12. Esophagus
Long, tube-shaped structure made of smooth muscle that takes food from mouth to the stomach

13. Stomach Regions Cardiac region Fundus
Body (greater and lesser curvature)
Pyloric region

14. Stomach Lining Mucus prevents stomach from digesting itself
Gastric glands secrete acids that breakdown food
PEPSIN - most important digestive enzyme for breaking down food
Mucus prevents stomach from digesting itself

15. STOMACH ULCERS

16. STOMACH MUSCLES:   
Longitudinal
Circular
Oblique

17. Food becomes…
Chyme – the semifluid mass of partly digested food expelled by the stomach into the duodenum

18. ACCESSORY ORGANS PANCREAS Secretes: Insulin which breaks down sugars
Other pancreatic juices that break down fat

19.  Liver
 Made of 1 large right lobe and 1 smaller left lobe

20. Major Liver Functions 1. Produces and secretes bile***
2.  Metabolizes fats, proteins, and carbohydrates
3.  Stores vitamins, glycogen, and minerals
4.  Detoxifies and purifies blood

21. Gall Bladder -under liver -stores bile & digests fat
Gallstones

22. Gallstones - made from built up cholesterol or bilirubin
*Can be as small as grain of sand or as large as a golf ball

23. Gallstones within the gall bladder

28. Approximately 7 meters long (~18-23 ft) 1. Duodenum 2. Jejunum
Small Intestine
 Approximately 7 meters long (~18-23 ft)
Starts at the pyloric sphincter
1.  Duodenum
2.  Jejunum
3.  Ileum
*Mesentery - membrane holds small intestines together, contains blood vessels

29. Main function of small intestines is ABSORPTION of NUTRIENTS

30. Intestinal villi - increase surface area to absorb nutrients, connect to vessels

31. Large Intestine Cecum – entrance from small intestines Appendix
Colon (4 parts)
Ascending
Transverse
Descending
Sigmoid
Rectum
Anus

32. Function of Large Intestine
The main job is WATER REABSORPTION...
Mass Movements (defecation) - removes undigested food

33. Colonoscopy is a screening technique to detect cancer.