NUTRITION AND
ENERGY SYSTEMS
IB SEHS
Chapter Three
Chapter Objectives
Chapter Objectives
Chapter Objectives
Nutrition
•The science that investigates the
relationship between physiological
function and the essential elements of
foods eaten.
Introduction
The 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
Macronutrients – nutrients that our body
needs in larger amounts to maintain health.
1.
a.
b.
c.
d.
Carbohydrates (CHO)
Fats
Proteins
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 Carbohydrates
1. 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 Acids
1. 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.