Lesson 5.1

The Three Energy Nutrients
 Carbohydrates
 Proteins
 Fats

• Carbohydrates are broken down into glucose and stored into the muscle as glycogen.
• Most easily broken down into this state which is why they are the first thing our body uses as a form of energy.

• Proteins are broken down into amino acids.
• Proteins are used for energy when the body is in starvation mode.

• Fats are broken down in to fatty acids and a glycerol.
• Fats are the LAST energy source which is used.

Adenosine DI phosphate
(missing a phosphate and can not produce energy)
Consumption of food
Food is broken down by the body into
GLUCOSE
(primary fuel source)
1 molecule of
GLUCOSE
=
2 molecules ATP
Energy production

• ATP = Adenosine TRI Phosphate
– 3 phosphates are present

Adenosine Triphosphate (ATP)
 Adenosine triphosphate (ATP)
 ATP is a usable form of energy for the body.
 Made in the mitochondrion
 Resynthesized in two ways
 Aerobically
 Anaerobically
ATP ADP + Pi + ENERGY

• ATP is the molecule that gives every cell in our body energy to function.
• All things in our body require energy in order to be able to function properly.
– Food metabolism
– Heart beat
– Muscles contract

• When you need energy it is on.
• When you don ’ t need energy it is being stored and not used.

Two Energy Systems
 Aerobic System
 In the presence of oxygen (O
2
)
 All of its metabolic activity will involve O
2
 Occurs in the mitochondria
 Leads to the complete breakdown of glucose

• With the presence of oxygen you are able to perform an activity over a long period of time with a balanced intensity.

• What is an example of “ aerobic activity ”
– Requires oxygen
• How does your body react?
– Heart rate increases
– Breathing increases

• Any activity longer than 90s
• Mitochondria of cells
• C6H12O6 + 6O2 +36ADP +36P i
--> 6CO2 + 36ATP 6H2O +
E

• When oxygen is reduced, it also bonds with 2 H+, and forms one H
2
O (inside the matrix)
• Oxygen is the final electron acceptor (This is why we need oxygen to live!)

http://www.youtube.com/watch?v=KU-B7G6anqw&feature=fvst

• Occurs in the muscle fiber, only using chemicals and enzymes readily available.
• Smaller amounts of energy are produced
• No oxygen is needed for this reaction
• Needed for short and medium length activities.
– Ex: weight lifting, short shifts in hockey

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• Within the ANAEROBIC and AEROBIC systems, there are 3 metabolic pathways by which ATP energy reserves are restored:
– ATP-PC pathway (anaerobic alactic)
– Glycolysis pathway (anaerobic lactic)
– Cellular respiration (aerobic)
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P ENERGY Creatine
ADP + P i
 ATP
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ATP-PC System
 ATP-PC System
(anaerobic alactic)
 First of two anaerobic energy pathways
 Relies on the action of stored ATP and phosphocreatine
 Yields enough ATP for
7-12 seconds of energy
 Provides highest rate of
ATP synthesis
PC + ADP ATP + CREATINE

• Plays an important role in sporting events which only last a few seconds, but require large bursts of energy.
– Ex: Olympic weight lifting, high jump, 50-100 m dash.
• HOWEVER – muscles do not have large supplies of phosphocreatine, and after about 10-15 seconds, body begins to rely on the seond system.

High Energy Phosphate System
Overview
Primary energy source:
Duration of activity:
Sporting events:
Advantages:
Limiting factors:
Stored ATP, CP
7 to 12 s
Weightlifting, high jump, long jump, 100 m run, 25 m swim
Produces very large amount of energy in a short amount of time
Initial concentration of high energy phosphates (ATP, PC)
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The Anaerobic Glycolytic System
Glycogen
ENERGY
Lactic Acid
ADP + P i
 ATP
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• A biochemical process that releases energy in the form of ATP from glycogen and glucose
• anaerobic process (in the absence of oxygen)
• The products of glycolysis (per molecule of glycogen):
- 2 molecules of ATP
- 2 molecules of pyruvic acid
• The by-product of glycolysis (per molecule of glycogen):
- 2 molecules of lactic acid
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• Starts when:
– the reserves of high energy phosphate compounds fall to a low level
– the rate of glycolysis is high and there is a buildup of pyruvic acid
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• The exercise intensity at which lactic acid begins to accumulate within the blood
• The point during exercise where a person begins to feel discomfort and burning sensations in the muscles
• Lactic acid is used to store pyruvate and hydrogen ions until they can be processed by the aerobic system
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Substrates for the anaerobic energy system
• The primary source of substrates is carbohydrate
• Carbohydrates:
– primary dietary source of glucose
– primary energy fuels for brain, muscles, heart, liver
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Carbohydrate breakdown and storage
Complex
Carbohydrates
Digestive system
Glucose
Blood
Stream
Circulation of glucose throughout body
Glucogenesis
Glucose stored in blood
Glycogen
Glycogen stored in muscle or liver
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

• This is a class challenge.
– Find an place on the wall, and the person who can perform a wall sit for the longest – will win a prize!
• Describe what you felt that made you want to stop?

• After 2 or 3 minutes of a sustained activity the body can not break down glucose fast enough to keep up.
• Lactic Acid builds up in the muscle fibers
• You are forced to slow down/stop – as it causes pain/discomfort in the muscle.

The Anaerobic Glycolytic System Overview
Primary energy source:
Duration of activity:
Sporting events:
Advantages:
Limiting factors:
Stored glycogen, blood glucose
12 s to 3 min
800 m run, 200 m swim, downhill ski racing, 1500 m speedskating
Ability to produce energy under conditions of inadequate oxygen
Lactic acid build up, H+ ions build up (decrease of pH)
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The Role of Three Energy Systems During an Allout Exercise Activity of Different Duration
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