Download x1-4 NutrMetab F12

6 types of nutrients –
Why we eat
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Which provide energy?
Water
Energy (calories)
“Building blocks”
Essential nutrients

Vitamins
Minerals
Primarily vitamins and minerals
Carbohydrates
Protein
Fats
Water is critical for body
functions
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The body is about 70%
water
Found both inside and
outside the cells
Functions
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Helps regulate body
temperature
Transports nutrients
Excretes waste products
Food as Fuel
Water
Nutrients supply energy

Protein
Carbohydrates
These nutrients
supply energy
(calories) to power
muscle contraction,
maintain body temp
and other cell
functions
Fats
What is a calorie?

Cells
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Break down high
energy molecules in
food in cellular
respiration.
Generate many
molecules of ATP.
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Way we measure the energy
stored in food
Definition:

A calorie is the amount of energy required to
raise the temperature of one gram of water by
1ºC.
Energy (Calories) from Nutrients
Nutrient
Carbohydrates

Energy
Carbohydrate 4 Cal/g
Protein
4 Cal/g
Fat
9 Cal/g
Primary source of
energy for living
organisms
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Simple sugars
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Polysaccharides
Table sugar, soft drinks
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Long starch molecules
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Fat is the most energy-rich nutrient
Alcohol contributes 7 Cal/g, but is not a nutrient.
Triglycerides:
the most common type of fat
Why do we need Fats?
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Dietary fats provide
 Energy for the body
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Fat-soluble vitamins
Essential fatty acids
Long-term energy storage in adipose
tissue
Kinds of Fatty Acids
Saturated Fatty Acids
(All Single Bonds C-C)
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Stored energy for later
use
Body structure

Reduce Heart
Disease Risk
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Trans-Fatty Acids (Hydrogenated)
Heighten Heart
Disease Risk
Not Found Naturally!
3 fatty acids attached
to a backbone of
glycerol
How the body uses fat
Heighten Heart
Disease Risk
Unsaturated Fatty Acids
(Some Double Bonds C=C)
Triglycerides
 Make up body fat
 95% of fat in food
Structure:
Cell membranes
The brain is 60% lipid
Every neuron is
insulated by the lipids in
its myelin sheath
Why do we need Protein?

Body structures
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Helps build muscle, bone, skin and
hair
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Regulates body functions
 Some hormones are proteins
Protects you from illness
 Antibodies are protein
Can be metabolized for energy
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Sources:
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Getting the right nutrients
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Alcohol provides energy (7 Cal/g)
But it has no necessary function in
the body
Toxic when consumed in large
amounts
meat, eggs, beans, nuts
What is a “good diet”?
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Is alcohol a nutrient?
Foods that provide energy
Vitamins, minerals and other essential
nutrients that the body can’t make
Basic advice for good nutrition
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Eat a variety of
foods
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Eat less
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Getting the correct amount of food
energy (cal)
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A new look for the Food
Pyramid
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USDA unveiled
“MyPlate” this year
Simpler than the Food
Pyramid
Fruit & vegetables
take up half the plate
Fruits, vegetables
and whole grains
don’t overeat
Avoid too much junk
food
Exercise more
What happens to food after
you swallow?
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Macromolecules in
food are broken
down →

Molecules small
enough for cells to
absorb
Foods are digested by enzymes
H2 O
Protein
Enzymes: proteins that speed
up chemical reactions
Amino acid
OH
H
Enzyme
(pepsin)
Carbohydrate
H2 O
Sugar
OH
H
Enzyme
(amylase)
Fat
Fatty acid
Glycerol
H2 O
H2 O
H
H O
OH
H
OH
H
H2 O
Enzyme (lipase)
Figure 22.3
Food is broken down
into its monomers that
are recombined into
new molecules
Cheese protein
(a polymer of amino acids
in a specific sequence)
Summary: Digestion of foods
Amino acid
monomer
Breakdown of protein
by human digestive
system
Amino acids
Absorption of amino acids by cells lining the small
intestine; transport via bloodstream to other cells
Human protein
Cells use amino acids from the cheese and
other foods to produce new human proteins
Figure 22.2-3
Harvesting energy from food
Where is the energy in ATP?
ATP
Or how food gets from
to
and body
structures
ADP
Why is ATP a good source of
energy for cells?
Some ways cells use energy
It is versatile–can be used in many
types of reactions

Its breakdown is easily coupled with
energy-requiring reactions

To build macromolecules
To transport molecules
across the membrane
It provides just the right amount of
energy for cellular reactions
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To power muscle contraction
Energy systems:
Metabolism
how our bodies
harvest energy
from food
3 ways our body makes ATP
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Immediate energy system (ATP-CP system)
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Anaerobic
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Creatine phosphate  ATP
CP is stored in muscles in small amounts.
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Broken down to replenish ATP stores
Produces instant energy for sudden movement
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e.g. a punch or a kick
Primary system during low- to moderate-intensity exercise
Produces most ATP
O2 required
All energy systems are used continuously!
Carbs are the main energy
source for glycolysis
The immediate energy system
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glycolysis system
Primary energy system during high intensity exercise
Produces a small amount of ATP
uses no O2
Aerobic system
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fastest supply of ATP
uses no O2
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ATP is generated
from the anaerobic
metabolism of
glucose and glycogen
Powers short,
maximal bursts of
energy
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Muscle action for lift
and hold
Glycolysis!
Carbs are the main energy
source for glycolysis
Glycolysis energy system
Blood glucose
Blood glucose
Stored
glycogen
Stored
glycogen
Doesn’t require O2 (anaerobic)
Aerobic respiration
Provides ATP quickly (~100 times faster than aerobic respiration)
Inefficient
Provides energy for intense activity lasting 1/2 - 2 minutes
If oxygen is limiting, ATP is
made by glycolysis
Does lactic acid buildup cause
muscle burn?
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Blood glucose
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Stored
glycogen
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Lactic acid
(by-product)
X
Aerobic respiration
Endurance events
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For longer periods of
activity the body
switches to the
Energy is obtained
from the breakdown
of fat (and
carbohydrate) in the
presence of oxygen
Lactic acid isn’t the culprit
Muscle soreness is caused
by actual muscle cell damage
and inflammation
Aerobic exercise
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aerobic system
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Once thought that lactic acid
causes muscle fatigue and
“muscle burn”
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It takes about 10
million
ATP molecules per
second to power an active
muscle cell
Requires fatty acids as
fuel
ATP production is
dependent on oxygen
availability
Metabolism of fuel molecules
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Glucose, simple sugars
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Glycolysis and aerobic
respiration work together
Glycolysis generates
a small amount of ATP
Glycolysis and
Aerobic energy production
Fatty acids
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Aerobic respiration only
O2
Athletic Performance
Aerobic respiration
Requires O2
Generates the most ATP
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Is protein used for energy?
Small amounts used as Fuel
Digested
to
Strength-and- Endurance
power events events
Main fuel
Glucose
Fatty acids
ATP production
Anaerobic
Aerobic
Bursts of ATP
More ATP, slower
No
Yes
Is oxygen used?
Where Is the Energy in Food?
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Built Into
Amino Acids
Proteins
Enzymes
Body Parts
Getting energy from food…
Stored in chemical bonds
between the C, H and O
atoms
Glucose
Enzymes + Mitochondria =
Highly Controlled
Metabolism is the process of harvesting this
energy and converting it to ATP
Cellular metabolism releases the energy in chemical bonds so
slowly that the energy can be harvested efficiently