GCSE Biology: Anaerobic Respiration

When cells are deprived of oxygen but still need energy they use anaerbic respiration.

Glucose => Lactic Acid + Energy

Lactic acid is toxic, and causes pain, so you stop doing the activity. The cells must remove the lactic acid. This requires a certain amount of oxygen. When oxygen supplies are restored, the oxygen is "paid" to the cells to remove the lactic acid. Ths amount of oxygen needed is called the oxygen debt.

Less energy is produced by anaerobic respiration than aerobic repiration. It is less efficient.

If you are running out of oxygen in your body, you must stop doing aerobic respiration and start anaerobic respiration if muscle contraction is to continue.