Energy for Muscular Contraction

Mark Arsenal
Flashcards by Mark Arsenal, updated more than 1 year ago
Mark Arsenal
Created by Mark Arsenal about 8 years ago
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Exercise Metabolism- Term 1 (Energy for Muscular Contraction) Flashcards on Energy for Muscular Contraction, created by Mark Arsenal on 04/15/2013.

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Question Answer
Give details of the differences between the 3 Muscle Fiber Types:
What is the Purine Nucleotide Cycle and what is its purpose? This is whereby IMP and Aspartate form to form Adenylosuccinate which is cleaved to release Fumarate. Fumarate is a TCA cycle intermediate as thus allows the TCA cycle to continue.
What is the Myokinase Reaction? And why is it turned on? The Myokinase is where Adenylate Kinase forms 1ATP and 1AMP from 2ADP. The Myokinase Reaction is only switched on during high intensity exercise when ATP levels fall. It generates ATP for energy but its primary purpose is to produce the AMP which stimulates the body to activate the energy producing pathways.
Energy is never made or used, it is just converted from 1 form to another. We roughly maintain ATP stores as degradation and synthesis are matched, but there is a lag.
Pathways for energy supply: Stored ATP, PCr Breakdown, Glycolysis, Electron Transport Train, Beta Oxidation. AMP levels is indicator to restore ATP levels.
Adenylate Pool Shows the energy charge of a cell. Between 0-1. 0=All ADP, 1= All ATP. Will never be all ADP or all ATP- will be somewhere in between.
Myokinase Reaction Forms ATP and AMP, but AMP is the more important product as it is a strong indicator to 'turn on' pathways regenerate ATP.
A build up of AMP (through ATP breakdown and Myokinase Reaction) prevents additional AMP formation by preventing the Myokinase Reaction, soo we break down the AMP to IMP to allow the Myokinase Reaction to continue. Muscular Contraction Cycle: 1) AP travels along neuron axon until myo-neural junction (synapse) where it releases Acetylcholine which diffuses to the sarcolemma and t-tubules. 2) Calcium is released from the Sarcoplasmic Reticulum which binds to Troponin which causes shift of Tropomyosin- exposing Myosin Binding Sites on the Actin Filament. 3) The Myosin 'heads' which contain both ADP and Pi bind to the binding sites on the troponin (Pi released) forming a cross bridge. 4) The ADP is used causing the Power Stroke and ATP binds to myosin heads. 5) Break down of the ATP (to ADP and Pi) causes the de-attachment of the cross bridges. 6) If Ca remains present the process continues. 7) To relax AP's stop and Ca is drawn back into the Sarcoplasmic Reticulum through Active Transport. 8) The energy for Active Transport is provided by the hydrolysis of ATP by both Ca and ATPase.
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