Cellular respiration is the chief process used by living animal cells to supply energy for their life processes. It involves the a glucose molecule, supplied by the digestive system, being combined with oxygen, supplied by the respiratory system. The glucose is broken apart, producing energy, stored in the form of ATP, and carbon dioxide and water as waste products. If the oxygen supply becomes scarce, or is nonexistent, the cell switches to anaerobic fermentation to produce energy. This method is faster, but not as productive as aerobic respiration. Cellular respiration produces 38 molecules of ATP as opposed to 2 molecules produced by fermentation. This is why athletes start their game full of energy, but depending on the level of energy expenditure, start to tire as the game wears on. At some point, rest is required to allow the body to restore the levels of depleted oxygen so the cellular respiration process may restore energy levels.
Cellular respiration when takes place in presence of Oxygen is called as Aerobic respiration, and in absence of oxygen it is called as Anaerobic respiration.
In Anaerobic condition the the pyruvate formed in glycolysis is chaneled to three pathways they are lactate cycle in humans also known as cori cycle.
The muscular energy requires energy which is obtained by the breakdown of glycogen(storage energy) by the process called glycogenolysis which then enter Glycolysis followed by Krab cycle.
when there is insufficient of supply of oxygen when there is intense muscular activity the energy must be released from the anaerobic respiration.
During anaserobic respiration Pyruvate is converted into lactate, and excess of latete formed is taken up by the liver which again convert lactate into pyruvate which is sent to bloodstream then to cells followed by glycolysis and the production of energy continues.
If production of lactate is excess it is pumped into the bloodstream and which lead to decreas in ph of the blood and low Ph that is acidic pH will cause damage to cell and can lead to death of the individual.