Ch 22 Nutrition and Digestion 22 1 Why do organisms need food o Digestion o Nutrients Food is physically broken down Substances that are used for energy raw materials and maintenance of the body s system o Carbohydrates o Lipids o Proteins o Vitamins o Minerals o Water Unneeded or unusable material that is eliminated after passing through the o Waste digestive system o Animals must eat for 2 reason To acquire the energy needed for all growth and activity To acquire the raw materials required for life 22 2What s on the menu o Types of animal diets Carnivores Animals that consume only other animals Animals that consume only plants Herbivores Omnivores 22 3 Calories count organisms need sufficient energy Animals that consume both plants and animals o The ENERGY required to raise the temperature of 1 gram of water by 1 degree Celsius o Components of energy expenditure Basal metabolic rate BMR The minimal energy expenditure of an organism at rest o Varies among species o Calculating BMR Body weight x energy needed hr x hr day animal s caloric needs Energy required for all activity Individuals generally need about 50 to 100 more kilocalories per day than their BMR 22 4 Water is an essential nutrient It transports nutrients and waste materials throughout the body Water constitutes between 60 65 of body weight Takes part in metabolic reactions Serves as solvent Lubricates many body parts Helps regulate body temperature o Proteins Animals consume 3 different types of macromolecules for calories Proteins Carbohydrates Fats enzymes Proteins provide raw materials for growth and for the production of Food sources of protein vary in amino acid composition Humans require 20 amino acids and 8 of these called essential amino 22 5 Proteins in food are broken down to build proteins in the body acids can only be supplied by the diet o Function o Source o Storage Once proteins are broken down the amino acids are used as the raw materials to build new complex protein such as hemoglobin and muscle Animals egg whites shrimp tuna poultry and meat Plants grains vegetables nuts seeds and legumes Amino acids are usually stored for less than half a day before being reassembled into proteins throughout the body Can be converted to fat and stored in fat cells o Proteins comprised of amino acids are the cellular workers o Types of proteins Complete proteins Contain all eight essential amino acids Almost all animal proteins are complete Incomplete proteins DO not contain all eight essential amino acids Almost all plant proteins are incomplete 22 6 Carbohydrate and lipids provide bodies with energy and more o Carbohydrates fuel for running your body Carbohydrates provide energy to fuel movement growth and all Function Source Storage cellular activities in the body Fruits vegetables and grains Carbohydrates are stored in the liver and muscle cells as glycogen for about a day before being broken down to provide energy Can be converted to fat and stored in fat cells o Sugars are the primary input for ATP production o Types of carbohydrates Simple sugars Glucose fructose and others Breakdown by glycolysis releases energy rapidly o Complex Sugars Digestible complex sugars starch Simple sugars bonded together such as sucrose table sugar or starch Bonds between simple sugars must be broken before the energy releasing reactions of glycolysis occur Indigestible complex sugars Fiber Complex carbohydrates that form structural parts of plants Indigestible in humans but has a significant role in digestion o Fats Long term Energy Storage Experts Fats provide a dense source of energy that can be efficiently stored in the body and they aid in keeping the body warm Function Source Storage Butter cheese oils eggs and meat Fats are stored in fat cells throughout the body o Saturated Fats Fatty acids have straight tails and can be packed together tightly Tend to be solid at room temp More likely to be stored as fat in the body o Unsaturated fats Fatty acids have kinked tails and cannot be packed together tightly Tend to be liquid at room temp Less likely to be stored as fat in the body o How and where do we store fats Converting complex carbohydrates into body fat Storing carbohydrates and proteins as body fat requires energetically expensive conversions reducing the amount of fat stored o 1 Energy is used to break down complex sugars o 2 Energy is used to break down simple sugars o 3 Energy is used to reassemble fragments into fatty acids o 4 Fatty acids are stored as body fat 22 7 Vitamins and minerals are necessary for good health o Essential Vitamins and minerals in the human diet Water Soluble B1 thiamin B2 riboflavin B6 pyridoxine B12 cobalamin Biotin C ascorbic acid Folic acid Niacin Pantothenic acid A retinol D cholecalciferol E tocopherol K menadione Fat Soluble Major Minerals Calcium Chlorine Magnesium Phosphorus Potassium Sodium Sulfur Trace Minerals Chromium Cobalt Copper Fluorine Manganese Molybdenum Selenium Zinc Iodine Iron 22 8 We convert food into nutrients in four steps o The digestive process in humans include four distinct phases 1 Ingestion 2 Digestion Food is taken into the body Large pieces of food are dismantled by physically and chemically breaking them into absorbable molecules 3 Absorption 4 Elimination Energy rich food molecules are taken into the cells of the body where they can be used for energy and building materials The remaining parts of the consumed foods mostly indigestible materials are discarded as waste products and much water reabsorption occurs 22 9 Ingestion is the first step in the breakdown of food o Salivary gland secrete an enzyme called alpha amylase that initiates the process of digestion Alpha amylase breaks the bonds holding together the starch molecule About 20 of the ingested starch is broken down in the mouth o Ingestion continues as food moves from the mouth down the esophagus and into the stomach 1 The tongue shapes the food into a ball and pushes it to the back of the mouth 2 A flap of tissue is moved over the entrance of the trachea when you swallow 3 After swallowing waves of smooth muscles contraction called peristalsis propel food down the esophagus and into the stomach 22 10 Digestion dismantles food into usable parts o Digestion is the process of dismantling large pieces of food physically and chemically breaking them down into absorbable molecules 1 Muscles in the stomach churn and physically break down and mix food 2 Gastric pits produce hydro chloric acid to activate