SEHS Topic 3.3 Nutrition and Energy
Systems
Annotate a diagram of the ultrastructure of
a generalized animal cell
Annotate a diagram of the ultrastructure of
a mitochondrion
Define the term cell respiration
The controlled release of energy in the form of ATP
from organic compounds in cells
Explain how adenosine diphosphate can gain and lose a
phosphate molecule
• The ATP molecule acts as a chemical 'battery',
storing energy when it is not needed, but able to
release it instantly when the body requires it.
• ATP works by losing the endmost phosphate group
when instructed to do so by an enzyme.
Cont’d
This reaction releases a lot of energy, which can then use to
build proteins, contract muscles, etc.
-The end product is adenosine diphosphate (ADP), and the
phosphate molecule.
-Additional energy can be extracted by removing a second
phosphate group to produce adenosine -monophosphate
(AMP).
-When the body is resting and energy is not immediately
needed, the reverse reaction takes place and the phosphate
group is reattached to the molecule using energy obtained
from food.
Explain the role of ATP in muscle contraction
• Phosphorylation of a protein = a conformational
change in that protein
• Skeletal muscle structure (review)
Actin, Myosin, Tropomyosin, Troponin,
Ca++ , ADP, & ATP
http://www.youtube.com/watch?v=hqynCsign8E
(SLIDING FILAMENT THEORY)
Describe the re-synthesis of ATP by the
ATP-CP system
• Creatine phosphate (aka PCr) is a high energy molecule that
is broken down to provide energy for the re-synthesis of
ATP that has been utilized during the initial stages of
exercise.
• serves as a rapidly available reserve of high-energy
phosphates in skeletal muscle and the brain
PCr and its role during intense exercise
• CAN NOT be used directly to drive muscle
contraction
• PCr + ADP + H  Creatine + ATP
• Provides energy QUICKLY but it is SHORT-LIVED (20
seconds)
• When typically used?
•
When performing explosive short activities:
•
sprinting, explosive weight training lifts,
shot-putting, high jump, periodic in game
movements…etc
• What does your body do once your PCr is used?
Lactic Acid (Lactate) Fermentation System
•
•
•
•
•
We’ve seen this before:
Glucose  Pyruvate  Lactate
Occurs in the cytoplasm
Its an anaerobic pathway (PCr is too!) = NO O2
Optimal for high energy demands of intense
exercise since the energy is produced quickly
• HOWEVER (like PCr) it provides only a short supply
of energy (ATP)…a couple minutes max… ALSO is
lowers muscle pH (lactic acid is a moderately strong
acid) = reduction in muscle’s ability to contract)
What energy system kicks in past 2:30 of
intense activity?
• AEROBIC CELLULAR RESPIRATION of glucose and
fat (beta oxidation)
Beta-Oxidation of Fatty Acids
• We also get ATP production from our fat
consumption and fat storage via beta-oxidation:
Explain the phenomenon of oxygen deficit
and oxygen debt
• Oxygen deficit – when oxygen need and oxygen
supply do not match during the first moments of
exercise
• Oxygen debt – (now better known as Excess Postexercise Oxygen Consumption….(EPOC)) – during
recovery from exercise , oxygen consumption
continues at a greater rate than needed at rest
KEY POINTS of E.P.O.C.
• O2 consumption remains elevated after exercise:
• 1. to rebuild ATP and Pcr stores in the cells
• 2. O2 is “borrowed” from hemoglobin and esp
myogloblin during initial stages of execise and must
be “repaid”
• Oxygen cost to help offset increase body temp
following intense exercise
Discuss the characteristics of the 3 energy systems and their
relative contributions during exercise
Cont’d
• Based on the information on the previous slide:
• Write an analysis of each energy system and
their roles during different types of exercise
(endurance athlete, baseball player, sprinter), as
well as the main nutrient(s) used and the
byproducts produced
• Fig 3.20 from the text will help