2. AP Biology 2006-2007 Animal Nutrition

3. AP Biology Getting & Using Food  Ingest  Digest  mechanical digestion  chemical digestion  enzymes (hydrolysis)  Absorb  diffusion  active transport  Eliminate intracellular digestion extracellular digestion

4. AP Biology Digestive systems Everybody’s got one!

5. AP Biology Human digestive system Alimentary Canal

6. AP Biology Ingestion  Mouth  mechanical digestion  Specialized teeth  chemical digestion  saliva  Amylase  Mucin  buffers neutralizes acid to prevent tooth decay  anti-bacterial chemicals kill bacteria that enter mouth with food

7. AP Biology Stomach  Functions  food storage  disinfect food  HCl chemical digestion  pepsin  enzyme breaks down proteins  secreted as pepsinogen activated by HCl But the stomach is made out of protein! What stops the stomach from digesting itself?

8. AP Biology Small intestine  Function  major organ of digestion & absorption  chemical digestion  digestive enzymes (pancreatic juice; sodium bicarbonate)  absorption through lining  over 6 meters!  small intestine has huge surface area (villi/microvilli)  Structure  3 sections  Duodenum, jejunum, ileum

9. AP Biology Pancreas  Digestive enzymes  Peptidases – breakdown proteins  trypsin  trypsinogen  chymotrypsin  Chymotrypsinogen  Pancreatic amylase  Lipase  Buffers  reduces acidity  alkaline solution rich in sodium bicarbonate small intestines

10. AP Biology Liver  Digestive System Functions  produces bile - made in gallbladder; emulsifies fats  stores fat-soluble vitamins (A,D,E,K)  stores iron

11. AP Biology Absorption by Small Intestines  Absorption through villi & microvilli  finger-like projections  increase surface area for absorption

12. AP Biology Hormones Involved  Gastrin – released by stomach cells in response to food OR senses responding to food  Secretin – produced by cells of duodenum in response to food; stimulates pancreas to produce NaHCO 3  Cholecystokinin- produced by small intestine in response to fats – stimulates bile and pancreatic juice to be released

13. AP Biology Absorption of Nutrients  Active (protein pumps) transport  pump amino acids, vitamins & glucose  allows intestine to absorb much higher proportion of nutrients in the intestine than would be possible with passive diffusion  worth the cost of ATP!

14. AP Biology Large intestines (colon)  Function  re-absorb water  vitamins made by bacteria (intestinal flora)  vitamins K, folic acid, B vitamins  intestinal gas is a by-product of bacterial metabolism

15. AP Biology Appendix Vestigial organ

16. AP Biology 15 Structural Adaptations Due to Diet - Dentition 1. Carnivores have large canines and incisors 2. Herbivores have small canines 3. Omnivores have medium sized everything

17. AP Biology 16 Structural Adaptations Due to Diet - Length of digestive system 1. Carnivore is smaller 2. Herbivore is longer due to cell walls - Ruminant digestion