1. DIGESTION The process of preparing your food for absorption http://www.mhhe.com/cgi-bin/netquiz_get.pl?qfooter=/usr/web/home/mhhe/biosci/genbio/animation_quizzes/animate_30fq.htm&afooter=/usr/web/home/mhhe/biosci/genbio/animation_quizzes/animate_30fa.htm&test=/usr/web/home/mhhe/biosci/genbio/animation_quizzes/animate_

2. What Happens to the Food We Eat?

3. Digestion • To break nutrients into smaller molecules • Physical Digestion • Mechanical breakdown of food particles • Chemical Digestion • Enzyme catalyzed breakdown of nutrient molecules

4. Absorption • Movement of digested nutrients through intestinal wall into: • Blood (water soluble nutrients) • Lymphatic system - > blood (fat soluble nutrients

7. Digestion:The Mouth • Chewing: physically breaks down food into smaller components • Food stimulates salivary glands to release saliva • Saliva contains amylase-breaks down starch • Saliva moistens food for easy swallow • Bolus: ball of chewed food mixed with saliva

8. DIGESTION:THE PHARYNX • Area responsible for swallowing • During swallowing, air passage is blocked by epiglottis • Blocks the food from entering the trachea and the lungs • Bolus is directed down the esophagus

9. DIGESTION:THE ESOPHAGUS • Connects the pharynx and the stomach • Bolus is moved towards the stomach by a contractile movement called peristalsis • Allows food to move through thoracic cavity, through diaphragm, to peritoneal cavity and the stomach (peristalsis)

10. Digestion: Chewing

11. Digestion: Swallowing

12. Digestion: Swallowing

13. DIGESTION:THE STOMACH • Food passes through a sphincter, (esophageal sphincter) a valve • Bolus mixes with stomach secretions to become chyme • HCl denatures proteins and kills bacteria • Mucus protects stomach wall from acid • Chyme released into small intestine through pyloric sphincter

14. DIGESTION:STOMACH • Stops salivary amylase and and slows lingual lipase activity (acid denatures enzyme) • Starts protein digestion: pepsin activated and starts protein digestion • Two Australians win Nobel Prize in medicine - More Health News - MSNBC.com

15. Digestion: The Stomach

16. DIGESTION:SMALL INTESTINE • 20 feet in length • divided into three segments: • duodenum • jejunum • ileum • 95% of digestion occurs in small intestine • Bile: made in liver, stored in gall bladder • Emulsifies fats

17. Digestion: Accessory Organs

18. Absorption

19. DIGESTION:SMALL INTESTINES • Pancreas: • Secretes bicarbonate into duodenum to neutralize stomach acid in the chyme • Secretes enzymes that act on • protein (proteases) • carbohydrate (carbohydrases) • lipids (lipases)

20. DIGESTION:LARGE INTESTINES • Absorbs water and some minerals • Supports growth of bacteria that produce Vitamin K • Supports growth of other bacteria that partially breaks down fiber • We are then able to absorb some of the breakdown products

21. Absorption and Transportation • All nutrients must pass through intestinal lining • Picked up by capillaries or lymphatic vessels

22. DIGESTION:CARBOHYDRATES • Begins in the mouth: salivary amylase • Amylase denatured in stomach • Small intestine: pancreatic enzymes breakdown large CHO’s(starch) to smaller • Small intestines: brush border cells produce disaccharidases (sucrase, maltase, lactase) • Breakdown sucrose, maltose, lactose • Absorption occurs in duodenum & jejunum

23. DIGESTION:PROTEIN • Protein digestion begins in the stomach • Denaturation by HCl • Pepsin breaks large proteins into smaller peptides • Pancreatic enzymes introduced into the duodenum • Break down peptides into amino acids, di- and tri-peptides • Intestine enzymes breakdown to amino acids

24. DIGESTION:LIPIDS • Mouth: Lingual Lipase, very little activity • Stomach: very little activity • Small Intestines: Major activity • Bile from gall bladder emulsifies • Enzymes from pancreas digest and makes the products ready for digestion • monoglycerides, glycerol, fatty acids • absorbed into cells of microvilli

26. Other Systems • Cardiovascular • Hormonal and Nervous • Storage • Liver • Muscle • Fat