Chapter 24 - Part I Nutrition, Metabolism, Body Temperature Regulation Introduction Nutrition - process of nourishing or being nourished living organism assimilates food and use it for tissue growth, maintenance & repair food is fuel (sustenance) for our metabolic engine 1 http://www.oznet.ksu.edu/fieldday/kids/pictures/kidsfield600/cg_wheat_closeup.jpg 2 http://www.shadetreemechanic.com/images/cummins%20turbo%20diesel%20engine%201.jpg 3 http://msnbcmedia.msn.com/j/msnbc/Components/Photos/050520/050520_embryo_bcol_7a.standard.jpg 4 http://baby-showers-hawaii.com/I%20love%20Baby%20Showers%20Hawaii2.JPG 5 http://www.pathguy.com/histo/016.jpg 2 3 4 Nutrients Digestion (catabolism) Acceleration Production (anabolism) Growth or repair 1 fuel replenishment fuel usage excess consumption Maintenance Cells Energy Production/Consumption Processes: 1. catabolism - breaking down of complex chemical compounds into simpler ones that liberates energy nutrients - oxidized and transformed into ATP ATP - provides chemical energy for metabolic machinery to produce new molecules 2. anabolism (a raising up) - building of complex chemical compounds from simpler compounds amino acids ? proteins usually requires energy in form of ATP Energy Production/Consumption Food energy: chemically determined & stated in terms of measurable units kilocalorie (large calorie) - amount of energy needed to raise temperature of 1 kilogram of water 1oC calorie (small calorie) - amount of heat required to raise the temperature of one gram of water from 14.5°C to 15.5°C nutritionists measure energy content of food in calories Analytical chemist http://www.erdc.usace.army.mil/pls/erdcpub/docs/erdc/images/Chemistry.jpg Nutrition Nutrient - substances promoting normal growth, maintenance, & repair essential nutrients - must get from a dietary source, not made by body cells Nutrient categories (6): major nutrients (3) - bulk of intake consisting of carbohydrates, lipids, & proteins minor nutrients (2) - minute amounts needed vitamins, minerals technical nutrient (1) ? water (no energy value) Source: www.mariposaweb.com/pizzafactory/images/calzone.jpg Balanced Diet Most foods contain a variety of nutrients should include representatives of each major food group Balanced diets - consist of foods from each of five major food groups: 1. grains 2. fruits 3. vegetables 4. meats & fish 5. milk products Food pyramid is only a general guide (children vs. adults) Calories: 120 Fat: Trace Calories: 225 Fat: 11 grams Baked potato 14 French fries Carbohydrates: Types & Uses Complex carbohydrates (polysaccharides) - starches found in bread, cereal, flour, pasta, nuts, & potatoes cellulose - not digested by humans but provides roughage (fiber), which increases the bulk of stool and facilitates fecal movement Simple carbohydrates (monosaccharides & disaccharides) - sugars found in soft drinks, candy, fruit, & ice cream Glucose - molecule ultimately used by body cells to make ATP other monosaccharides can be converted to glucose Galactose Glucose Carbohydrates: Dietary Requirements Glucose (con?t): neurons & RBCs rely almost entirely upon glucose to supply their energy needs excess glucose is converted to glycogen or fat & stored Minimum amount of carbohydrates needed to maintain adequate blood glucose levels =100 grams per day starchy foods & milk - have nutrients such as vitamins and minerals in addition to complex carbohydrates refined carbohydrates (candy and soft drinks) - only provide an energy source and are referred to as ?empty calories? Source: http://images.postcards.net/vp/food.jpg Carbohydrates: Starch v. Cellulose Starch polymer beta-linkage alpha-linkage Difference between starch & cellulose is bonding type both are composed of glucose monomers Starch demonstrates branching Lipids: Types & Uses Triglycerides & triacylglycerols: most abundant dietary lipids meal calories not used immediately by tissues are converted to triglycerides & transported to fat cells to be stored per gram, fat has more than twice calories of CARBO or PRO Cholesterol: stabilizes cell membranes precursor of bile salts & steroid hormones not an energy source Source: www.bioviestinta.com/images/lipid%20bilayer2.jpg Lipids: Types & Uses Phospholipids - found in all cellular membranes & myelin sheaths (nervous tissue lecithin) Essential fatty acids - linoleic & linolenic acid, found in most vegetables (e.g. peanuts) must be part of dietary intake essential fatty acids are needed to absorb fat-soluble vitamins dietary fats: 1. are an easily stored energy source 2. cushion organs 3. have insulating properties Lipids: Dietary Requirements Higher for infants and children than for adults no current recommendation on fat intake but American Heart Association suggests that: fats should represent less than 30% of total caloric intake saturated fats should be limited to 10% or less of total fat intake Saturated vs. unsaturated fats saturated fats (hydrogenated) - meat & dairy foods; few plant products (coconut) unsaturated fats (dehydrogenated) - seeds, nuts, and most vegetable oils ? incidence of atherosclerosis & coronary heart disease Daily cholesterol intake should not exceed 200 mg Source: http://biology.clc.uc.edu/graphics/bio104/fatty%20acid.jpg Lipids: Taste Source: http://www.littledebbie.com/images/products/zebra1.gif Popular refrigerator magnet for dieters There?s nothing ?little? about Little Debbie not unique to this processed food product (plenty of examples) Little Debbie Zebra Cakes
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