1. Energy for Muscle Contraction Flashcards
what is the 1st law of thermodynamics?
energy is neither created or destroyed
= the ability to do work depends on the conversion of one form of energy to another
Describe the concept of turnover in metabolism
molecules are constantly being used (degraded) and restored (synthesized). Particularly ATP.
Explain the importance of ATP as the common chemical intermediate for cell processes
it is used to power muscle contractions and other forms of cellular work.
Why is ATP homeostasis important?
cells, tissues and organs are designed to maintain constant cellular ATP over wide ranges of rates of turnover. it is used for a lot of processes in the body
What are the 3 energy systems that maintain ATP homeostasis
immediate
non-oxidative (glycolytic)
Oxidative (aerobic)
What is the role of PCr in energy metabolism?
combines with ADP to make one molecule of ATP and creatine. It is a high energy phosphorylated compound
It provides a reserve of phosphate energy to regenerate ATP
what is the role of ADP in energy metabolism?
combines with PCr to make ATP.
2 ADP can also join to make one ATP and one AMP which is important during high intensity exercise - the myokinase reaction
what is the role of AMP in energy metabolism?
An increase in AMP causes the restoration of ADP into ATP
it can also activate enzymes involved in energy metabolism eg glycogen breakdown and glycolysis
what is the adenylate pool and what’s its relation to the cell energy charge
= the pool of ATP, ADP and AMP concentrations that can then be used to calculate the energy charge of a cell
what are the energetics of muscle contraction?
- Rigour state - myosin head @ end of range. Bound ATP is released
- ATP binds to the myosin head
- Detachment - myosin head detaches from actin filament
- Attachment - ATP splits into ADP and Pi so is now ready to attach to actin
- Attachment - mysoin binds weakly
- Rotation - Pi is released from the mysoin so the head strongly binds
- Rotates - shortening begins. Actin slides past myosin + head rotates.
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what are the major differences between the 3 muscle fibre types?
Type 1 --> Type IIa --> Type IIx Fibre diameter= Small - intermediate - large Mitochondria vol = high = middle - low Myosin ATPase - low - high - high Glycolytic capacity= low -high-high Oxidative capacity= high-med/high-low Speed= slow-fast-fast fatigue resistance=high-moderate-low force capacity=low-intermed-high
How do you calculate energy charge?
ATP + ADP + AMP
what does the energy charge measure? and what does it regulate?
it measures the extent to which the total adenine pool of a cell is phosphorylated.
It regulates the rate of ATP resynthesis during exercise
In different muscle fibre types the myosin ATPase activity displays different pH sensitivity. it also determines what?
the rapidity of ATP hydrolysis in the myosin heavy chain region and thus the velocity of sarcomere shortening
