Digestive System and Nutrition Organs Process of Digestion Nutrition

Path of Food through the Digestive System mouth pharynx esophagus Produces pepsin, HCl Produces peptidases, maltase, lactase stomach small intestine large intestine anal canal Peristalsis: Muscular contractions that move food through the digestive system

Accessory Organs and Glands Produce salivary amylase salivary glands Produces pancreatic amylase, trypsin, lipase Produces bile liver gall bladder pancreas Stores bile

Process of Digestion and Absorption Mouth Teeth chew food into smaller pieces Salivary amylase (enzyme in saliva) begins starch digestion Tongue mixes food with saliva to form bolus to be swallowed Starch in bun has been broken into smaller chains of sugars

Process of Digestion and Absorption Stomach HCl acid unfolds proteins Pepsin (enzyme) begins protein digestion, breaking some peptide bonds esophagus sphincter pyloric sphincter muscularis layer has three layers of muscle mucosa layer has rugae gastric pit gastric gland Protein in beef has been broken into smaller chains of amino acids cells that secrete gastric juice Contains pepsin, HCl, mucus

Process of Digestion and Absorption Small Intestine Large surface area due to numerous villi Bile emulsifies lipids Pancreatic and intestinal enzymes digest carbohydrates, lipids, proteins Amino acids and sugars absorbed into blood Lipids absorbed into lymphatic system villus lacteal blood capillaries venule arteriole lymphatic vessel Carbohydrate, Protein and Fat have been digested and absorbed

Digestion occurs by Hydrolysis of Macromolecules Emulsification: physical dispersion of lipids into smaller droplets carbohydrate protein + Hydrolysis: chemical separation of subunits pancreatic amylase bile salts fat globules trypsin emulsification droplets peptides maltase hydrolysis cell of intestinal villus peptidase lipase Hydrolysis glucose amino acids pH = basic pH = basic pH = basic lymphatic capillary blood capillary blood capillary Carbohydrate digestion Protein digestion Fat digestion

Process of Digestion and Absorption Large Intestine Absorbs water Absorbs salts (minerals) Absorbs some vitamins Stores waste for later elimination Calcium from cheese has been absorbed. Fiber from tomatoes and lettuce remains.

Distribution and Use of Nutrients Liver regulates nutrient entry into blood detoxifies blood stores iron and fat-soluble vitamins makes plasma proteins stores and releases glucose produces urea from amino acids produces bile destroys old red blood cells helps regulate blood cholesterol

Applying Your Knowledge Stomach Mouth Large Intestine Small Intestine Where are fats digested? Where do proteins unfold? Where does starch digestion begin? Where is water absorbed?

Nutritional Recommendations Macronutrients Carbohydrate Fat Protein Water Micronutrients Vitamins Minerals VEGETABLES GRAINS FRUITS MEAT & BEANS MILK Use fats in small amounts

June 2011 Recommendations Balancing Calories  Enjoy your food, but eat less.  Avoid oversized portions.   Foods to Increase  Make half your plate fruits and vegetables.  Make at least half your grains whole grains.  Switch to fat-free or low-fat (1%) milk.   Foods to Reduce  Compare sodium in foods like soup, bread, and frozen meals, and choose the foods with lower numbers.  Drink water instead of sugary drinks.     

Carbohydrates: Dietary Recommendations 58% of calories from carbohydrates No more than 10% of calories from simple, refined sugars Emphasize Complex Carbohydrates Starch Fiber (cellulose) Naturally-occurring simple carbohydrates Fructose from fruit Lactose from milk

Fats: Dietary Recommendations < 30% of calories from fats < 10% of calories from saturated fats Limit cholesterol to 300 mg/day Avoid “trans” fatty acids in partially hydrogenated products Emphasize Unsaturated fatty acids from vegetables, fish, legumes, and nuts Oils: mono- or polyunsaturated

Proteins: Dietary Recommendations 12% of calories from proteins 8 essential amino acids obtained from Lean sources of animal protein Complementary plant proteins Beans + Grains Beans + Seeds

Vitamins Organic compounds used in metabolic reactions as coenzymes or antioxidants Water Soluble: B vitamins, C Fat Soluble: A, D, E, K Adequate amounts come from a varied diet that includes vegetables and fruits May prevent cancer and cardiovascular disease

Minerals Inorganic substances required by the body Macrominerals needed in large amounts, eg. calcium Microminerals needed in smaller amounts, eg. iron May need to emphasize certain foods to obtain iron or calcium May need to limit foods high in sodium

Applying Your Knowledge Calcium Vitamin C Lipid Carbohydrate Protein Which one is a mineral? Which macronutrient should supply the greatest number of calories in the diet? Which one may protect against cancer?

Reading a Nutrition Label More info at http://www.fda.gov www.fda.gov/food/labelingnutrition/consumerinformation/ucm078889.htm#twoparts

Calorie Percentage Calculations Number of grams Caloric value Total calories These should add to 100%. 12 x 9/250 = 0.432 x 100 = 43.2% 3 x 9/250 = 0.108 x 100 = 10.8% www.fda.gov/food/labelingnutrition/consumerinformation/ucm078889.htm#twoparts 31 x 4/250 = 0.496 x 100 = 49.6% 5 x 4/250 = 0.080 x 100 = 8.0% 5 x 4/250 = 0.080 x 100 = 8.0%