11.18.2008

ATP

Introduction
Adenosine triphosphate (ATP) is a multifunctional nucleotide (molecules which comprise the structural units of RNA and DNA) whose most significant function is to aid in the process of intracellular energy transfer. As such, ATP transports chemical energy within cells for metabolism. It is produced as an energy source during the processes of photsynthesis and celullar respiration and consumed by many enzymes and a multitude of cellular processes. Below is a picture of the ATP compound:

This complex compound is stored in all cells, particularly muscles. It is only from the energy released by the breakdown of this compound that the cells can perform work. The breakdown of ATP produces energy and ADP (adenosine diphosphate).

Creatine Phosphate (CP) is a chemical compound stored in muscles, which when broken down aids in the manufacture of ATP. It is the combination of ADP and CP that produces ATP.

Actively contracting muscles obtain ATP from glucose stored in the blood stream and the breakdown of glycogen stored in the muscles. Exercise for longer periods requires the complete oxidation of carbohyrates or free fatty acids in the mitochondria. The carbohydrate store will last approximately 90 minutes and the free fatty store for several days.

ATP & Energy Pathways
The three energy systems contribute at the start of exercise but the contribution depends upon the individual, the effort applied and the rate at which energy is transferred. The graph below depicts how the energy systems contribute to the manufacturing of ATP over time when exercising at 100% effort. The threshold (T) indicates teh point at which the energy system is exhausted. Training will improve your threshold times.


Sources

Wikipedia: Adenosine Triphosphate, Unknown Author
Sports Coach, Brian Mackenzie

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