Overview of Energy Production

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Overview of Energy Production

• PED 5230

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ATP Universal Energy Donor
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ATP

• ATP H2O ? ADP P energy.
• Enzyme - ATPase
• 7.3 kcal/mol (11 kcal/mol)

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ATP
Energy Out
Energy In

• Where does this energy come from?

• What is the energy used for?

• Swiveling of myosin heads
• Separation of myosin head from actin

ADP

• CrP
• Carbohydrates
• Fats
• Proteins

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Creatine Phosphate

• CrP ADP ? ATP Cr.
• Enzyme - Creatine Kinase
• Very fast, almost immediate, re-production of ATP
• Very limited production of ATP
• ATP Cr ? CrP ADP
• This ATP comes from other energy systems during
  rest or light exercise

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Creatine Phosphate
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ATP and CrP

• CrP produces ATP so rapidly that a reduction in
  ATP levels are rarely seen even at maximal
  exercise.

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Gimme fuel, Gimme fire Gimme that which I
desire - Metallica
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Carbohydrates

• Carbohydrates
• Glucose
• Glycogen (stored glucose molecules)
• Anaerobic or Aerobic
• Glycolysis (Anaerobic)
• Glucose ? 2 ATP 2 Lactate 2 H
• Fast ATP production
• Limited ATP production

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Carbohydrates

• Aerobic
• Glucose O2 ? 36 ATP CO2 H2O
• Fast (for aerobic fuel)
• Limited supply of stored carbohydrate inside the
  body

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Fats

• Fats (e.g. Palmitate) O2 ? 129 ATP CO2 H2O
• Slow
• Larger molecule
• Mobilization
• Require more O2

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Available Energy Sources
From Wilmore and Costill
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Available Energy Sources
Tale 3-4
?
?
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Protein

• During exercise.
• Kreb cycle intermediates (help with energy
  production)
• Glucose-Alanine cycle (an indirect energy source)
• Oxidation (a direct energy source)
• Only 5-10 of total energy during exercise

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Krebs Cycle
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Glucose-Alanine Cycle

• Alanine converted to glucose in the liver
• Glucose be used to supply the CNS with glucose
  during
• Starvation
• Prolonged exercise

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Glucose-Alanine Cycle (figure 8-10)
Muscle
Liver
Glucose
Blood
Alanine
NH3
Urea
Kidney
Alanine
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Oxidation

• Protein oxidation during exercise decreases with
  conditioning

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Energy Systems

• Anerobic
• ATP-PCr
• Glycolysis
• Aerobic
• 3. Oxidation

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Energy Systems
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Energy Systems
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ATP-PCr
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Glycolysis
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Glycolysis

• Glucose, a six carbon sugar, is split into two,
  three-carbon molecules.
• Products
• 4 ATP (2 Net)
• 2 NADH
• 2 Pyruvate (Pyruvic acid)

glycogen
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Glycolysis
Figure 5-7
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Glycolysis

• What happens to the ATP made in glycolysis?
• What happens to the NADH?
• What happens to the pyruvate?

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Oxidation

• Oxidation the process of removing an electron
  from a molecule (e.g. Hydrogen)
• The electron provides the energy needed to reform
  ATP from ADP and P
• Subsystems
• Krebs Cycle
• Electron Transport Chain
• Beta Oxidation

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Where Does Oxidation Occur?

• Mitochondria (plural)
• Outer membrane
• Intermembrane space
• Inner membrane

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The Krebs Cycle
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Key Enzymes

• Isocitric Dehydrogenase (IDH)
• The rating limiting enzyme
• Inhibited by ATP, NADH, acid (lactic acid) etc.
• Stimulated by ADP, NAD, etc.

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The Krebs Cycle

• From 1 pyruvate
• 3 CO2
• 1 ATP (GTP)
• 4 NADH
• 1 FADH

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Actyl-CoA

• Sources of Actyl-CoA
• Glucose (Pyruvate)
• Fatty acids
• Amino acids
• Combines with OAA to form citric acid

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The Krebs Cycle

• An imperfect cycle
• Products
• CO2
• ATP
• H
• Which product is most important?
• Why?

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NADH and FADH

• Transport H to Electron Transport Chain

• NADH give 3 ATP for every H
• FADH give 2 ATP for every H

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Electron Transport Chain
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Electron Transport Chain

• Inner mitochondrial membrane
• Oxidation removal of electrons (H)
• Series of steps from higher to lower energy
• A chemical and electrical gradient is formed

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Electron Transport Chain

• Phosphorlyation ADP P ? ATP
• Re-entry of H provide energy (Fig. 6-10)
• Linked to the formation of water
• Oxygen is the final electron acceptor
• H2O

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Oxidation of Carbohydrates
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Glycolysis
Krebs Cycle
Electron Transport Chain
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GLYCOLYSIS
Start with glucose
2 NADH
2 net ATP
End with 2 pyruvates
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KREBS CYCLE
Start with pyruvate being converted to Acetyl-CoA
End up with 4 NADH 1 FADH ATP CO2
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KREBS CYCLE (Detailed)
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KREBS CYCLE AND THE ELECTRON TRANSPORT CHAIN
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• ALL TOGETHER
• GLYCOLYSIS
• KREBS
• ELECTRON TRANSPORT CHAIN

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• ALL TOGETHER
• GLYCOLYSIS
• KREBS
• ELECTRON TRANSPORT CHAIN

• ALL TOGETHER
• GLYCOLYSIS
• KREBS
• ELECTRON TRANSPORT CHAIN

NAD NADH
Lactic Acid
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Glycolysis
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Aerobic or slow glycolysis

• Glucose 2 Pi 2 ADP 2 NAD ? 2 pyruvate 2
  ATP 2 NADH 2 H2O
• The 2 NADH move into the mitochondria.
• Pyruvate also moves into the mitochondria

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Anaerobic or fast glycolysis

• Glucose 2 Pi 2 ADP ? 2 lactate 2 ATP H2O.
• The NADH are used to convert pyruvate to lactate.
• Keeps H level low, at least temporarily.

Mitochondria
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"There are three side effects of acid enhanced
long-term memory, decreased short-term memory,
and I forget the third." - Timothy Leary
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Lactic Acid

• Initially, most glucose is used aerobicly
• As more glucose is required, due to an increase
  in intensity, more NADH is produced in the
  sarcoplasm
• If the additional NADH cannot transfer H to
  mitochondria, then lactate levels increase
• The more O2 that is supplied to the mitochondria,
  the more NADH will be transfer into the
  mitochondria and the less lactic acid that will
  be produced.

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Lactic Acid

• Production
• Excess NADH in sarcoplasm
• Inadequate oxygen supply to mitochondria
• Rapid rate of glycolysis
• Removal
• Slow twitch muscle fibers
• Liver
• Heart

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The Cell-Cell Lactate shuttle

• Figure 5-20.
• Lactate from FT fiber can shuttle to ST fibers
  and be oxidized

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Glucose Paradox
Figure 5-3
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Lactic Acid Turnover

• During heavy exercise, lactate levels increase
  because production is greater than removal.
• High amounts of lactic acid cause fatigue but not
  delayed muscle soreness.

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Lactate levels after a 200-m swim at the same
speed.
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"I find no sweeter fat than sticks to my own
bones." - Walt Whitman
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Burning Fats During Exercise

• Mobilization of Fats
• Circulation and Uptake
• Activation
• Translocation
• Beta (?) Oxidation
• Krebs/ETC Oxidation

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Fat Mobilization
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Activation and Translocation

• Figure 7-5
• FA bind to acyl-CoA (1) Fatty acyl-CoA
• Move to inner membrane
• CoA is removed and FA attaches to carnitine
• (2) Fatty acyl-carnitine to the inside of the
  mitochondrion
• Carnitine is removed
• Another CoA added, (3) Fatty acyl-CoA

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?-Oxidation

• Degrades the (3) fatty acyl-CoA to (4) acetyl-CoA
  by cleaving two carbons at a time
• First carbon is the alpha ? carbon
• Second carbon is the ? carbon
• Palmitate (16 carbons) will provide 8 acetyl CoAs

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?-Oxidation

• Acetyl Co-A enters Krebs cycle
• Each acetyl Co-A results in 12 ATP
• 1 NADH and 1 FADH
• Palmitate (16 carbons) will provide 129 ATP
• Triglyceride of stearate (18 C) 460 ATP

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Fat Burns in a Carbohydrate Flame

• Beta oxidation produces acetyl-CoA
• Acetyl-CoA must bind with oxaloacetate (OAA) in
  order to enter the Krebs cycle
• OAA needs to constantly be replaced.
• Pyruvate can be converted to OAA
• Without adequate pyruvate, there is insufficient
  OAA needed for acetyl-CoA to enter the Krebs
  cycle.

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Beta Oxidation
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Fat Utilization During Exercise

• Rest
• 60 fat, 35 carb, 5 protein
• Exercise
• Burn more of everything
• Greater percentage comes from carbohydrates
• Active muscle cells burn mostly all carbohydrates
• Other inactive cells burn fat
• Very hard exercise
• Burn less fat due to an increase in lactic acid
  which inhibits L-HSL and fat mobilzation

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Fuel Sources
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Fuel Sources
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