Anaerobic Respiration is the breakdown of food substances in the absence of oxygen. Anaerobic respiration releases less energy than aerobic respiration.
Anaerobic respiration occurs in certain microorganisms, for example, yeast. Yeast respires aerobically in the presence of oxygen. Without oxygen, yeast carries out anaerobic respiration.
Anaerobic respiration releases less energy than aerobic respiration. The little amount of energy released is enough for the yeast to survive, though it cannot be very active under such conditions.
Equation for anaerobic respiration :
Glucose -> Ethanol + Carbon Dioxide + Small amount of Energy
Energy conversions in muscle cells
Muscle cells normally respire aerobically. When less oxygen is available, muscle cells will also respire anaerobically for a short period of time.
Muscle cells carry out anaerobic respiration to produce extra energy as maximum aerobic respiration is unable to produce energy fast enough to meet demands.
Equation for anaerobic respiration in your muscles:
C6H12O6 (Glucose) -> 2C3H6O3 (Lactic Acid) + Small amount of energy
The small amount of energy released in anaerobic respiration, together with that produced in aerobic respiration, is sufficient to keep the muscles contracting.
Since there is insufficient oxygen to meet the demands of vigorous muscular contractions, the muscles are said to incur an oxygen debt.
Lactic acid concentrations start to build up in the muscles and this causes fatigue and muscle pains.
Lactic acid is transported to the liver and oxidized to produce oxygen. This energy is used to convert the remaining lactic acid back into glucose when the body is no longer short of oxygen. When the lactic acid is used up, the oxygen debt is repaid.
Glucose is then transported back to the muscle.