Nutrition & Digestion

1. Nutrition & Digestion Ch.18

2. Nutrition • Nutrition – process by which we obtain food • Nutrients – substances used in metabolism. • Nutrients obtained thru major food groups. • Bread/Cereal • Fruit/Vegetable • Meat/Fish/Poultry • Dairy • Oils/Fats

3. Types of Nutrition • Autotrophs – can make their own food • Heterotrophs – can’t make their own food

4. Types of Digestion • Mechanical • Break food into smaller pieces. • Increases surface area for digestion. • Chemical • Breaks down food molecules into their basic building blocks. Ex) Carbs to monosaccharides • Intracellular – within the cell • Extracellular – outside the cell

5. Adaptations for Nutrition • Protozoan – intracellular diges, osmosis • Hydra – osmosis, tentacles, stinging cells, gastro-vascular cavity. • Earthworm – alimentary canal, typhlosole • Grasshopper – gizzard/teeth, diges glands

6. Basic Nutrients • Carbohydrates – monosacchrides • Proteins – amino acids • Lipids – glycerol + fatty acids • Vitamins – organic cmpds needed in small amts • Minerals – inorganic ions needed in small amts • Water – most basic & important nutrient

7. Balanced Diet • 2000 – 4000 Calories/day • Diet should supply more than just the energy needed for that day.

9. Human Digestive System • 9 meters long w/ specialized sections • Duct glands – secrete to specific location • Ductless glands – individual cell secretions • Mucus protects most surfaces

11. Mouth • Teeth – mechanical digestion • Tongue – tastes food, assists swallowing • Saliva – lubricates food for swallowing, • Mostly Water (90%) • Amylase digests Carbs to Disaccahrides

12. Esophagus • Connects mouth to stomach. • Epiglottis – covers trachea so food enters the esophagus when you swallow. • Composed of circular muscles. • Peristalsis pushes food along with a wave of muscle contractions.

13. Stomach • Stores food 3-4 hours • Churns food – mechanical digestion • Gastric juice – chemical digestion • Pepsin digests proteins to large peptides • Hydrochloric acid • activates enzyme • kills bacteria • curdles milk • Ulcers are holes in stomach lining

14. Liver • Accessory Digestive Organ • Produces Bile – emulsifies fats • Gall Bladder stores bile & excretes cholesterol

15. Pancreas • Juices digest all 3 food groups • Amylase: Carbs to disacchrides • Lipase: Fats to glycerol & fatty acids • Trypsin: Proteins to small peptide chains • Sodium Bicarbonate – neutralizes acids • Insulin – regulates sugar absortion

16. Small Intestine • Digestion is completed here • Maltase, Sucrase, Lactase digest disaccharides • Lipase digests remaining lipids • Eripsin completes protein digestion to AA’s • Absorption of all nutrients occurs here • Villi increase surface area of intestine • Microvilli are extensions of villi cells • Blood vessels absorb water soluble nutrients • Lacteals absorb fat soluble nutrients

18. Large Intestine • Undigestible materials pass thru here • Water is reabsorbed • Feces is concentrated remains • Bacteria feed on remains and produce… • Vitamin K • Vitamin B12 • Appendix is a vestigial organ (no function)

19. Rectum • Feces is stored here for elimination