Nutrition and Digestion SBI 3U

BIG IDEA Animals obtain and process nutrients for energy and growth from the food they eat!

It All Starts With a Healthy Diet … Nutrients: the chemicals in the food you eat that help your body perform all its functions. Six types in food: Carbohydrates Proteins Macronutrients Fats Water Vitamins Micronutrients Minerals

Processing Molecules Digestive system disassembles food we eat Body uses these as source of energy or assembles them into more complex molecules Uses them to build and maintain cell structure and function

1. Carbohydrates Main source of energy for the body Composed of C, H, O atoms Three main types: - monosaccharides – one sugar (ex. glucose) - disaccharides – two sugars joined (ex. sucrose) - polysaccharides – many sugars joined (ex. cellulose)

GLUCOSE STARCH Main fuel supply for cells Cells break it down and extract stored energy Extra glucose stored as fat STARCH Whole grain cereals, bread, rice and potatoes Complex carb Broken down into simple sugars and absorbed into blood Excess blood sugar converted into GLYCOGEN Glycogen stored in liver and muscle and fat cells When body needs it, glycogen broken down into glucose

CELLULOSE Fruits, veggies, whole grain breads, bran, wheat germ Often called FIBRE Human digestive system can’t break it down Helps move food and wastes through digestive system Helps reduce heart disease?

2. Proteins Complex molecule constructed from 20 kinds of smaller molecules called AMINO ACIDS 8 essential amino acids – cells cannot make so must get in diet Meat, milk, eggs and cheese provide 8 essential Protein functions Control of chemical reactions Muscle movement Transporting oxygen Structure Hormones Defense Last source of energy

3. Fats Also called LIPIDS Molecules formed from 3 fatty acids and a glycerol molecule Store energy in body Help absorb fat soluble vitamins Provide insulation Fatty acid chains Glycerol

SATURATED FATS Carbon atoms have max number of hydrogens bonded to them Solid at room temp Most animal fats (butter, lard) Bad fats Can build up within walls of blood vessels and block blood flow

UNSATURATED FATS TRANS Fruits, veggies, fish, olive oil At least one double bond with Carbons so missing Hydrogens Liquid at room temp Better for you then saturated fats TRANS Man made to accept more hydrogens Solid at room temp Margarines, fying fast food AVOID!!!!!

4. Vitamins organic molecules body requires in small amounts regulate cell functions, growth, and development Carbs, proteins and fats are building blocks; vitamins are tools that help put them together fat soluble (will dissolve in fats) A,D,E,K Can be stored in fatty tissue for future use water soluble (will dissolve in water) C and B Cant be stored so must be attained in diet

5. Minerals Inorganic nutrients; don’t contain carbon Calcium, iron, phosphorous, copper, sodium, zinc Need to consume these to replace what you lose in sweat, urine and digestive wastes

6. Water Our bodies are 55 – 60 % water needed for chemical reactions, to digest food, and to eliminate waste products. also necessary to maintain your blood volume, to regulate body temperature, and to keep your skin moist. We need about 2L of water per day

Food As Fuel In cells, glucose makes cellular energy by reacting with oxygen during cellular respiration 40% of energy from food goes to performing cell functions Other 60% converted to thermal energy (heat) 100-watt light bulb?

Calories The amount of energy required to raise the temperature of 1g of water by 1°C needed to provide energy so the body functions properly. number of calories in a food depends on the amount of energy the food provides. Fuel Calories Per Gram Fat 9 Carbohydrate 4 Protein Alcohol 7

Energy Requirements Metabolism: set of chemical reactions that occur in living organisms that are necessary to maintain life Catabolism: metabolic reactions that break down larger molecules into smaller ones Anabolism: the metabolic reactions that use energy to produce larger molecules from smaller subunits Metabolic Rate: the rate at which the body converts stored energy into working energy. Generally five trends (see p397)

number of calories a person needs depends on age, height, weight, gender, and activity level.

Read Before You Eat

Fighting Disease Nutraceutical – a substance that is purified from foods and taken like a medicine to provide health benefits Omega-3 fish oil pill taken as a supplement Functional Food – food that has health benefits beyond the normal nutritional benefit of the food OJ enriched with calcium Eggs enriched with omega-3 Milk enriched with vit D Designer food industry Probiotic yogurt

Canada’s Food Guide

Please Complete Mini Investigation in textbook p398 Explain why your body must process food in order for you to use it. What is the difference between glucose and glycogen? Why do you need to eat a variety of foods each day? Why is it important to ensure your diet has the right amount of vitamins and minerals? Have you changed your eating habits based on diets and nutritional claims presented in the media? Why or why not?