What is lactic acid fermentation in muscle cells?

Lactic acid fermentation in muscle cells is a process that produces energy under anaerobic conditions.

Lactic acid fermentation is a metabolic process that occurs in the muscle cells when there is a lack of oxygen, or under anaerobic conditions. This typically happens during intense exercise when the demand for energy exceeds the supply of oxygen. The process begins with glycolysis, where glucose is broken down into pyruvate, producing a small amount of ATP (adenosine triphosphate), which is the cell's main energy currency.

However, in the absence of oxygen, the pyruvate cannot be fully oxidised in the mitochondria to produce more ATP. Instead, it undergoes fermentation. In muscle cells, this is lactic acid fermentation. The pyruvate is reduced to lactic acid by the enzyme lactate dehydrogenase, using NADH produced in glycolysis. This regenerates NAD+, which is needed for glycolysis to continue and produce more ATP.

The lactic acid produced can accumulate in the muscles, contributing to muscle fatigue. However, it can also be transported to the liver, where it can be converted back to glucose when oxygen levels are restored. This is known as the Cori cycle.

In summary, lactic acid fermentation in muscle cells is a crucial process that allows energy production to continue under anaerobic conditions. It is a temporary solution that enables the muscles to keep working, even when the oxygen supply is insufficient.