Anaerobic Respiration involves the incomplete breakdown of glucose in which oxygen is absent, and a very small amount of energy is released as compared to aerobic respiration. Very few C-H bonds are broken due to which less energy is released. It produces various products that depend on the type of organism. For instance, in animals, lactic acid is produced while in yeasts, carbon dioxide and ethanol is made (also called as fermentation).
In animals, when there is a high amount of exertion, the energy demand in the muscles increases. Also, as many muscles engage in contracting, the oxygen becomes limiting for some of them, hence they start doing anaerobic respiration. As a partial breakdown of glucose happens, lactic acid is produced. The lactic acid can build up in muscles causing fatigue, hence to replace it, heavy breathing begins that replaces the oxygen debt (oxygen debt is the amount of oxygen needed to clear up lactic acid by reacting with it and forming water and carbon dioxide). The word and chemical equations are given below respectively.
Glucose →Lactic Acid + Less amount of energy
In yeast cells, anaerobic respiration/fermentation is exploited industrially; like in baking for bread making and brewing to form beer. Carbon dioxide and ethanol are produced as the products. The word and chemical equations are given below for anaerobic respiration respectively.
Glucose →Carbon Dioxide + Ethanol
C6H12O6 →2CO2 + 2C2H5OH