9 terms

Physiology - Energy Systems

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ATP/PC system
ATP which is the only immediately available energy source and only lasts for 2-3 seconds
Phosphocreatine (PC) is the additional fuel needed to resynthesize ATP
Creatine kinase breaks down PC which releases energy
The energy is then used to resynthesise ATP
Site of reaction: Sarcoplasm
Energy Yield: 1 ATP
Energy intensity: High intensity
Energy duration: max 10 seconds
Advantages of the ATP/PC system
ATP re-synthesises very quickly
No oxygen is needed
Provides energy for high intensity exercise
No harmful by-products
Disadvantages of the ATP/PC system
low ATP yield
low stores of PC
Short duration
Glycolytic System
PC stores deplete quickly and to continue high intensity exercise more energy is needed.
We use the additional fuels glucose and glycogen.
Glycogen is broken down by GPP into glucose
Glucose is broken down by PFK to pyruvic acid.
Energy is released here to re synthesis ATP
Due to lack of Oxygen Pyruvic acid is broken down by LDH to lactic acid
Site of reaction= Sacroplam
Energy yield= 2ATP
Energy intensity= high
Energy duration= 1 min max - 3 min submax
By products= lactic acid
Advantages of the Glycolytic system
Oxygen isn't required large fuel stores in liver,muscles and blood.Provides energy for high intensity exercise. Quick process as there are only a few chemical reactions involved. It has a higher energy yield than the ATP/PC system. Lactic acid can be recycled.
Disadvantages of the Glycolytic system
Lactic acid is produced as a by product which Lowers the PH in muscle cells and enzyme activity
Low ATP yield and recovery can take a while
Stimulates pain receptors
muscle fatigue and pain
short duration of only 10 seconds to 3 minutes
Aerobic System
Used during low-moderate intensity exercise

Aerobic Glycolysis: occurs in the sarcoplasm and is where glycogen is broken down to glucose using the enzyme glucose phosphorylase (GPP)
Glucose is catalyzed by PFK and converted to pyruvic acid. This process releases 2 ATP.

Coenzyme A forms acetyl CoA which starts the Krebs cycle as citric acid.

Krebs cycle: Co2, 2 ATP and hydrogen is produced. Occurs in the matrix.

Electron transfer chain: NAD and FAD carry hydrogen. Occurs in the cristae. 34 ATP is produced and H2O.
Food fuel: Glycogen, Glucose and fats.
Energy duration: 3 minutes onwards
Advantages of the Aerobic system
Large amounts of fuels can be used
High ATP yield and long duration of energy production
No fatiguing products
Disadvantages of the aerobic system
Delay for oxygen and complex series of reactions
Slow energy production (can only use for sub- maximal exercise)
Free fatty acids demand 15% more O2 for the breakdown
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