1. Digestive System

2. Oral Cavity (Mouth)
Teeth, tongue and salivary glands begin mechanical and chemical digestion

4. Salivary Glands Made up of 2 types of secretory cells
Serous cells produce a watery secretion containing enzymes, ions and a tiny bit of mucin
Mucous cells produce a stringy, viscous solution called mucous

5. Composition of Saliva Slightly acidic (pH 6.75-7.00) 98% water
Electrolytes (Na+, K+, Cl-, PO4-, HCO3-)
Salivary amylase – digests carbs
Mucin – lubricates food
Lysozyme – inhibits bacterial growth
IgA - antibodies
Metabolic Wastes – urea and uric acid

6. Esophagus
Peristalsis – muscular contractions that push bolus to stomach

7. Stomach Muscular sac where protein digestion begins
Has volume of 50 ml empty to 4L (1 gallon) full

8. Gastric Bypass Surgery

9. What happens in the stomach?
Churning action mechanically breaks down food
HCl denatures proteins to prepare for digestion
Pepsin chemically digests proteins
Intrinsic factor is secreted – needed for vit. B12 absorption in small intestine
Food is changed into a creamy paste called chyme

10. Pyloric Sphincter Controls Chyme Delivery to Small Intestine
Slow delivery of chyme is necessary because…
Chyme is very hypertonic
Chyme has low pH

11. Accessory Organs for Digestion
Liver – makes bile which emulsifies fats
Gallbladder – stores bile and delivers it to small intestine
Pancreas – creates digestive enzymes to complete digestion and secretes bicarbonate to neutralize the acidic contents of the stomach

12. What is Bile??
Bile salts emulsify fats (makes small droplets) and helps fat absorption
Bilirubin is the breakdown product of hemeglobin (green). The breakdown product of bilirubin gives feces its brown color.
The liver produces ml daily

13. Small Intestine
Duodenum – (25cm) bile duct and pancreatic duct attach here
Jejunum (2.5m)
Ileum (3.6m)
Chemical digestion is completed and absorption of nutrients occurs here
It takes 3-6 hours for chyme to travel through

14. Segmentation – mixes and moves the chyme

15. Intestinal surface area for absorption is 200m2
Villi

16. Large Intestine
Absorbs water from indigestible food residue and eliminates semisolid feces.
Subdivisions:
Cecum
Appendix
Colon
Rectum
Anal canal

17. Bacterial Flora
Colonize the colon and ferment indigestible carbohydrates like cellulose
Synthesize B complex vitamins and Vitamin K

18. USDA – United States Department of Agriculture My Pyramid Plan

19. MEAT & BEANS
EXERCISE
VEGGIES
GRAINS
OILS
MILK
FRUITS