IB SEHSChapter Three

NUTRITION AND ENERGY SYSTEMS

Chapter Objectives

Chapter Objectives

Chapter Objectives

Nutrition

•The science that investigates the relationship between physiological function and the essential elements of foods eaten.

IntroductionThe choice of what to eat and drink are influenced by…

*Biological Needs*Environmental Needs

Both determine quality, quantity, and balance of our food supply

Figure 3.1*Shows the relationship between the human body (Internal environment) and external environment (culture, economics), nutritional requirements and health.

*Good Nutrition is a powerful and modifiable factor for health promotion.

*Optimal nutritional results in normal development, good health and a high quality of life.

*Under-nutrition (hunger) and malnutrition (vitamin deficiency) and over-nutrition (obesity) can cause impaired growth and/or development and diseases.

Introduction

•The combination of several nutrients influence the function of the human body. •The combination and amount of nutrients a person takes in determines their health and well-being.•Nutrients are transported via the blood stream and metabolized in the cells of different organs. •Nutrients do not function in isolation.•Nutrients interact with each other in food, in the digestive system, in the blood and in the final site of function…. the cell.

Classification of Nutrients

1. Macronutrients – nutrients that our body needs in larger amounts to maintain health.

a. Carbohydrates (CHO)b. Fatsc. Proteinsd. Water

Carbohydrates•Carbohydrates are synthesized by plants from water and carbon dioxide using sun energy.

•These generate chemical composition of carbohydrates is:

(CH2O)n

n=determines the number of molecules that influence body function and impact on health

Carbohydrates

•Main function is to act as metabolic fuels and energy stores.

•In the cells CHO (glucose) is oxidized back into water and carbon dioxide. This reaction produces energy.

Carbohydrates

•CHO is the most widespread source of energy.

•1 Gram of CHO yields 4 calories.

•In plants CHO are stored as starch.

•In animals CHO are stored as glycogen.

Types of Carbohydrates1. Monosaccharides – the simplest form is made

of one molecule and is easily absorbed by the body.

Examples – glucose, fructose, galactose

2. Disaccharides – Two monosaccharides form disaccharides with the loss of one molecule of water.

Examples – sucrose (glucose-fructose combination)

Type of Carbohydrates

3. Oligosaccharides – These CHO have three to nine molecules

Example – Maltodextrin

4. Polysaccharides – These CHO have molecule chains longer than ten molecules

Example – starch and glycogen

Types of Carbohydrates

•Di, Oligo, and Polysaccharides need to be broken down to monosaccharides in the gut before they can be absorbed and transported to the organs.

• Some Oligo and polysaccharides are indigestible or poorly digestible are called dietary fiber.

•Dietary fiber is mostly found in the cellular walls of plants such as celluolose. Dietary fiber is important for:

• Prevention of constipation• Prevention of heart disease

Fats

•Dietary fats are found in a variety of animal and plant sources.

•1 gram of fat yields 9 calories.

Fats•Important for:

•Energy•Protection of vital organs•Control body temperature (thermal insulation)•Synthesis of hormones•Vitamin D (Sterols)•Cell membranes (sterols and phospholipids)•Transport of fat soluble vitamins

Fats

•Major dietary fats are broken up into:

•Triglycerides

•Phospholipids

•Sterols

Triglycerides•Make up 95% of dietary fat.•One molecule consists of one glycerol molecule and three fatty acids.•These fatty acids can be identical or a combination of different fatty acids.•The structure of the fatty acids determines the characteristics and biological function of triglycerides.•Can be stored in adipose tissue and used as an energy source for a prolonged period of time.

Fatty Acids – Essential

•Essential FA – Some FA are classified as essential because our body is lacking the enzymes necessary to synthesize them and therefore depends on their supply through food.

•Essential FA are found in plant oil such as sesame seeds, corn, linseeds and walnuts.

Fatty Acids - Characteristics

•Are chains of carbon atoms with hydrogen attached, and a methyl group (CH3) and a carboxyl group (COOH) on each end (Refer to figure 3.4 page 54).

•There are different kinds with different structures.

Types Of Fatty Acids1. Saturated fatty acids (SFA) – with the

maximal number of hydrogen atoms (four) on each carbon.

2. Unsaturated fatty acids (UFA) – where two hydrogen atoms are missing form double bonds between two carbon atoms and become unsaturated.

3. Monounsaturated fatty acids (MUFA) – with a single double bond in the chain.

4. Polyunsaturated fatty acids (PUFA) – shaped by multiple double bonds.

Types of Fatty Acids

1. Omega-3 fatty acids – PUFAs that have the first double bond located between the third and fourth carbon atom from the methyl end.

2. Omega -6 fatty acids - PUFAs that have the first double bond located between the sixth and seventh carbon atom from the methyl end.

Research has shown that optimal balance of omega-3 and omega-6 fatty acids in the diet is important to maintain adequate inflammatory and immunological responses.

Water•A person can only survive a few days without water.•Between 50-60% of total body weight is water.•Responsible for bathing cells, aids in fluid and electrolyte balance, maintains pH balance and transports molecules and cells throughout the body.•Major component of blood, which carries oxygen and nutrients to the body.•6-8 glasses of water are needed daily for optimal function.