Lactate metabolism
glycolysisThe process by which glucose (the respiratory substrate) is broken down into pyruvate. This stage involves the phosphorylation of glucose and intermediates (during the energy investment stage) which leads to the generation of more ATP during the energy pay off stage. This results in a net gain of ATP. is the breakdown of glucose into two pyruvateThe substance produced by the breakdown of glucose in the cytoplasm during the first stage of aerobic respiration and fermentation. molecules. During glycolysis, NADH is produced when hydrogen ions are passed to the coenzyme NAD.
When oxygen is available (aerobic conditions), pyruvate molecules progress into the citric acid cycle.
Anaerobic conditions
During vigorous exercise, oxygen is not available (anaerobic conditions) and pyruvate undergoes fermentation in the cytoplasmThe living substance inside a cell (not including the nucleus). of the cell.
Hydrogen ions are transferred from the NADH to pyruvate. This produces lactate.
The removal of hydrogen ions from NADH regenerates NAD. NAD is needed to maintain ATP production through glycolysis
In aerobic conditions, most ATP is produced in the electron transport phase. Electron transport is not supported in lactate metabolism, so this results in much less ATPStands for 'adenosine triphosphate' which is the high-energy chemical that transfers chemical energy in cells. being produced than in aerobic respiration.