1. Small & Large Intestine D IGESTIVE & E XCRETORY S YSTEM

2. S MALL I NTESTINE  Is nearly 21 ft long outstretched  Divided into 3 sections:  Duodenum-10 in  Jejunum-8 ft  Ileum- 12 ft  Found coiled up in the abdominal cavity

4. D IGESTION C ONTINUED  Secretions from the liver & pancreas enter the duodenum to continue the digestion of chyme  As chyme enters the duodenum, the intestinal mucous glands release large quantities of mucus  Glands in the lining of the small intestine release enzymes that complete digestions & prepare for absorption

5. S MALL I NTESTINE E NZYMES  Peptidases: break down proteins  Nucleosidases: break down nucleic acids  Enterokinase: released by epithelial cells and is an enzyme activator  Intestinal amylase: breaks down sugars  Intestinal lipase: breaks down fatty acids

6. S MALL I NTESTINE H ORMONES  3 regulatory hormones are secreted from the SI mucosa  Gastric inhibitory peptide: it inhibits gastric secretion, churning, and activates insulin secretion  Secretin: inhibits gastric secretion  Cholecystokinin (CCK): slows gastric emptying

7. A BSORPTION  The second function of the digestive system  During this process the end products of digestion, amino acids, monosaccharides, glycerol, and fatty acids are absorbed into the blood & lymph vessels  The structure of the small intestine is what allows absorption to work

8. I NTERNAL S TRUCTURE OF THE SI V ILLI & M ICROVILLI  The lining of the SI is highly folded and is covered with millions of fingerlike projections called villi (villus)  The cells on villi have projections on their cell membranes called microvilli  These structures together give a surface area of about 250 m 2  Nutrients are absorbed using diffusion & active transport

9. I NTERNAL S TRUCTURE OF THE S I C APILLARIES & LYMPH VESSELS  Inside of each villi are capillaries and tiny lymph vessels called lacteals  Lacteals absorb glycerol and fatty acids  Capillaries absorb amino acids and monosaccharides

11. S TRUCTURES OF THE SI

12. L ARGE I NTESTINE  Aka the colon  AKA the cecum  Final organ of digestion  5 major parts  Ascending colon  Transverse colon  Descending colon  Sigmoid colon  Rectum with anal canal

14. L ARGE I NTESTINE  Most of the absorption of nutrients & water is completed in the small intestine  9 L of water enter the SI daily, but only 0.5 L of water is present in the material that enters the LI  Only nutrients produced by bacteria and the remainder of the water are absorbed in the large intestine  Peristalsis moves this material in the colon toward the rectum  The material solidifies into feces and the intestinal wall lubricates it with mucus