Anaerobic respiration takes place when aerobic respiration cannot. In some cases (Prokaryotes) there are no organelles to carry out aerobic respiration, but in other cases aerobic respiration only is not enough (when a muscle exercises).
The anaerobic pathway creates an oxygen deficit in the body. At the moment of relaxation, the body will require larger volumes of air/oxygen to “pay off” the oxygen debt.
1) In the cases in which there are no organelles to carry out aerobic respiration, anaerobic respiration follows the ethanol pathway:
- It is a irreversible reaction, during which energy is released by “fermentation.”
2) In cases in which aerobic respiration does not suffice, the lactate pathway oxidises the molecules of reduced NAD and reduced FAD (Why is that needed? Well 1. There is no more oxygen, 2. reduced NAD and reduced FAD stop releasing hydrogen, 3. no more molecules of NAD and FAD available to continue glycolysis).
Lactate is a toxic substance for the body (that’s why muscles hurt). It is transferred to the blood through blood plasma, and then to the liver, where 20% of the lactate is converted to H2O and CO2. The rest is packed up in glycogen molecules for a later use.
The reason for which the lactate pathway cannot carry on forever is that the process of converting lactate to H2O and CO2 requires oxygen.