I Digestive Systems A) Function 1) breakdown food into smaller molecules 2) absorption of food molecules Summary of digestive process B) Components 1) Vary in different organisms a) Range from Simple ------ Complex C) Simple 1) diffusion of unicellular organisms 2) active intake of food by phagocytosis (form food vacuoles) D) Complex - Animal digestive systems 1) Primitive example - simple tube, one opening (Hydra and Flatworms) 2) Segmented tube - some division along the tube, gizzard and intestines, two openings (Earthworms) 3) Vertebrate digestive systems - highly differentiated, complete division of labor + accessory glands a) different functions - digestion, absorption, storage E) Basic layout of vertebrate digestive system - human 1) mouth - teeth for physical breakdown of food, some chemical digestion of starches 2) Esophagus (+ pharynx) connect mouth with stomach, can be enlarged as in birds for temporary storage 3) Stomach - storage and chemical breakdown of foods a) acids - break down all types of foods b) enzymes for digestion of proteins 4) Small intestine - absorption and digestion cells and cell parts 5) Large intestine - absorption of water 6) Rectum - storage of feces 7) Accessory glands - deliver enzymes to small intestine for digestion a) pancreas - enzymes for digesting proteins and starches b) liver - provides bile through gall bladder to break down fats II Diet and Nutrition A) Diet - what an animal eats 1) Diet studies document what prey species an organism feeds on B) Nutrition - assessment of the quality of the diet 1) Amount of energy in food a) use of the bomb calorimeter 2) Measure the % composition of proteins, fats, carbohydrates in diet 3) number of calories per day in the diet C) 4-9-4 rule - used to calculate composition of food 1) proteins - 1g burns 4 cal (multiply the number of grams by 4) 2) fats - 1g burns 9 cal (multiply the number of grams by 9) 3) carbohydrates - 1g burns 4 cal (multiply the number of grams by 4) 4) Hyothetical Example - BLT
| Molecule | # of grams | Calories/g | Total calories | % of Diet |
| Proteins | 25g (25%) | 4 | 100 | 15.3% (100/650) |
| Fats | 50g (50%) | 9 | 450 | 69.4% (450/650) |
| Carbohydrates | 25g (25%) | 4 | 100 | 15.3% (100/650) |
D) RDA standards for a healthy diet 1) Protein - 10%, Fat - 30%, Carboh. - 60% 2) Caloric intake a) influenced by gender, age and activity level b) males - 15-25 yrs should be 2800 cal/day c) females - 15-25 yrs should be 2200 cal/day d) balance between intake (eating) and expenditure (exercise) E) Goal of RDA standards 1) Reduce proteins - excess is turned into fat 2) Reduce fat content associated with heart disease 3) Carbohydrates are OK if they are complex sugars found in vegetables and fruits F) Nutritiondata.com - online food analyzer G) Your food and Exercise III Other considerations - Rounding out the diet A) Minerals - inorganic (needed in small amounts) 1) Ca - bone and muscle, found in dairy products, vegetables 2) Na - nerve and muscle cells, found in salts, most foods 3) K - nerve and muscle cells, found in most foods 4) Fe - blood cells (hemoglobin), found in whole grains, vegetables 5) Summary from Campbell - see symptoms associated with deficiencies for minerals above B) Vitamins 1) A - vision, found in milk, eggs, yellow fruits, fish liver 2) B (B6) - metabolism, found in whole grains, vegetables 3) C - fight infection, cartilage and bone, found in fruits and vegetables 4) K - blood coagulation, found in vegetables, bacteria in large intestine 5) Summary from Campbell - - see symptoms associated with deficiencies for vitamins above IV Well balanced diet and the Food Pyrmaid A) Diet composition (1 = eat the least of, least healthy - 5 = eat the most of, most nutritious) 1) refined sugars, fats and oils 2) milk - meat 3) fruit & vegetables 4) grains, pasta B) Goals of the pyramid 1) reduce intake of fats (reduce risk of heart problems) C) New views on the Food Pyramid 1) Rearranging the food pyramid - from ABCNews.com 2) Dr. Willet's new food pyramid Top - foods to use sparingly red meats,animal fats, white rice and bread, potatoes, some pasta and sweets margarine, vegetable shortening and trans-fatty acids, coconut and palm oils deep-fried foods Middle - moderate amounts fish, poultry, eggs Nuts and legumes Bottom - larger amounts vegetables (crunchy vegetables), fruits Bottom - largest amounts whole grain foods (wheat and high fiber, etc.), plant oils V History of Food A) For fun - check out these web sites 1) The food timeline 2) History of food and agriculture
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