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Digestion and Nutrition Chapter 30 (M) Food and Nutrients Food Any substance, either raw or processed which is meant for human consumption Nutrients The components of food that the body can use for growth, repair and energy How Nutrients are Obtained Heterotrophs get nutrients in various ways Types of Nutrients Carbohydrates Proteins Fats Vitamins Minerals Water Food as Fuel Carbohydrates, fats and proteins are all used to generate ATP Fats9 Calories/gm, Proteins and Carbs 4Calories/gm 1 Calorie (kilocalorie)= 1000 calories Basic Calorie need 2200 for female teens, 2500 males Essential nutrients Must these be ingested, cell can’t construct Essential Fatty Acids Linoleic Acid Essential Amino Acids 8 AA Vitamins water soluble (can be excreted) and fat soluble( excess might cause damages), reqd for enzyme function Minerals reqd, but large amts can cause damage Nutrition and a Balanced Diet Balanced Diet provides nutrients in adequate amounts and enough energy to maintain a healthful weight Balancing your diet Food labels Food guide pyramid The Food Guide Pyramid The Food Guide Pyramid Number of calories depends on: Age Sex Size Whether or not you are a pregnant or breastfeeding woman Whether you have a chronic illness The National Academy of Sciences recommends the following calorie categories: 1,600 calories - Many sedentary women and some older adults 2,200 calories - Children, teenage girls, active women and many sedentary men. Women who are pregnant may need around 500 calories more per day and an additional 300 calories for breast-feeding 2,800 calories - Teenage boys, active men and very active women The Food Guide Pyramid can be extremely useful - whether you want to gain weight, lose weight or maintain your weight. Eating a healthy diet is a little easier if you base your choices on the Food Pyramid. MyPyramid USDA's newest food pyramid guide Encourages consumers to make healthier food choices To get regular exercise Food groups are arranged in vertically bands, instead of horizontal ones Band width indicates portion size The wider the band, the more food from that group should be eaten. The Digestive System Converts food into small molecules that can be used by all cells of the body Food is processed in four phases by the digestive system Stages of Food Processing Ingestion: eating or drinking Digestion : Breaking food into smaller molecules 1. 2. • • 3. 4. Mechanical Chemical (Enzymes) Absorption: nutrient molecules enter blood, the circulatory system transports it through out the body Elimination: undigested material passes out of the body The Digestive System Functions like a series of tube like organs which pass through the body from the mouth to the anus Alimentary Canal Alimentary Canal can be about 30’ long Accessory organs Pancreas, Liver, Gallbladder secrete enzymes that are released into the food tube Digestion in the Mouth It all begins in the mouth . . . Teeth, tongue Salivary glands Mucus Amylase Only carbohydrates are digested here SWALLOWING AND PERISTALSIS GLOTTIS AND EPIGLOTTIS Peristalsis Rhythmic muscular contractions propel a bolus of food The human digestive system Digestion in the Stomach Muscular organ Acts as a reservoir where food is prepared for digestion in the SI Produces Gastric Juices Stomach Functions Food Storage 2. Mechanical Digestion 3. Chemical Digestion Secretions: 1. Mucus 2. EnzymePepsinogen 3. HCL 1. CHYME semi-fluid food mixture leaves. Protection from Self-Digestion Protective lining Main enzyme -Pepsin is inactive Pepsinogen when secreted Digestion in the Stomach Pepsinogen Comes in contact with HCl Pepsin Pepsin converts proteins into peptones Acidity of Gastric juices kills some bacteria that enters with food Gastric Juices stimulated by psychological and chemical means Peristaltic process of moving chyme into the SI takes place for 6hrs Small Intestine Digestion in the Small Intestine Main stage of Digestion As chyme enters the SI secretes juices that are alkaline and neutralizes the acidity SI maltase,lactase,sucrase breaks disaccharides Liver secretes bile emulsifies fats Dipeptidases dipeptides into AAs Pancreas Trypsin & Chymotrypsin break down proteins Amylase converts starch into maltose Lipase breaks fats Process is complete in about 4 hrs Pancreas Secretes Hormones Sodium bicarbonate Digestive enzymes Lipase Trypsinogen Amylase Liver Secretes Blood clotting enzymes Stores glycogen Bile Stored in gall bladder Emulsifies fat The structure of the Small Intestine LARGE INTESTINE = COLON 1. Anatomy: 2. Functions a. Reclaim water b. Synthesis of vitamins by E. coli Feces Rectum Anus Diarrhea Constipation Can you name the parts and tell what they do?
