The ENERGY supply of MUSCULAR ACTIVITY
The ATP content in the muscle slightly (about 5 mmol /kg wet weight tissue – 0,25-0,4%) and kept at a constant level, since the increase in the concentration of ATP inhibits myosin ATPase, and a fall below 2 mmol/kg disrupts the operation of the CA-pump reticulum and inhibits the process of relaxation. The ATP can ensure the implementation of intensive work only for a very short period of time of 0.5-1.5 C or 3-4-year-single cuts the maximum force. Further muscular work is ensured thanks to the rapid resynthesis of
ATP from products of its decay. Sources of energy for the resynthesis of ATP are creatine phosphate and ADP.
The resynthesis of ATP can be carried out under anaerobic and aerobic conditions. Under normal conditions, the resynthesis of ATP occurs predominantly aerobic, and muscle hard work, when oxygen delivery to the muscles is difficult, tissue increases anaerobic mechanisms of ATP resynthesis. In the skeletal muscles of the person identified 3 types of anaerobic and one aerobic path resynthesis of ATP.
To anaerobic mechanisms include:
1) creatinphosphokinase (alactate) mechanism for the resynthesis of ATP by perestrelyany between the creatine-phosphate and ADP;
2) glycolytic (lactate) mechanism for the resynthesis of ATP during anaerobic breakdown of muscle glycogen or blood glucose with the formation of lactic acid;
3) miakinsky mechanism, which performs the resynthesis of ATP by the reaction of perestrelyany between two ADP with the participation of myokinase (adenilatkinazy).
Aerobic mechanism of ATP resynthesis involves the reaction of oxidative phosphorylation. Energy aerobic oxidation substrates are glucose, fatty acids, partially amino acids, lactic acid and ketone bodies.
Each mechanism has a different energy capabilities, which are characterized by the following criteria evaluation of the mechanisms of energy production: maximum power . the speed of deployment . metabolic capacity and efficiency . Maximum power – this is the highest rate of formation of ATP in this metabolic process. She limits limit the intensity of the work performed through this mechanism. The speed of deployment is estimated by the time to reach the maximum capacity of a given path resynthesis of ATP from the beginning. Metabolic capacity reflects the total amount of ATP that can be obtained in this mechanism resynthesis due to the size of the reserves of energy substrates, capacity limits the volume of work performed. Metabolic efficiency is that part of energy which is accumulated in macrorhyncha links ATP, it determines the efficiency of the work performed and the estimated total value of the coefficient of performance (COP) representing the ratio of the total useful energy to its total allocated in this metabolic process.
The overall efficiency of energy conversion by metabolic processes into mechanical work (Eat) depends on two values: a – conversion efficiency released during metabolic transformations of energy in the energy resynthesizing ATP, i.e. the efficiency of phosphorylation (Eph); b – the efficiency of conversion of ATP into mechanical work, i.e. the efficiency of the Electromechanical coupling (Her):
Eat = (EF/Her) ∙100
The Electromechanical efficiency of conjugation in the processes of aerobic and anaerobic metabolism are approximately the same and amounts to 50%, the efficiency of phosphorylation of the highest in alactate anaerobic process is about 80% and the lowest in anaerobic glycolysis – an average of 44%, in the aerobic process 60%.
Criteria for evaluation of the mechanism of energy supply of muscular activity