Oxygen Use & Debt
Biology: Cambridge International GCSE Supplement, topic 12.2.2
Anaerobic Respiration
If muscles are not supplied with enough oxygen during long periods of activity (like exercise), then muscle cells may start to respire anaerobically. This can lead to oxygen debt:
Lactic acid
- Lactic acid is a by-product of anaerobic respiration.
- Lactic acid is toxic and can build up in muscles, leading to muscular pain and fatigue.
- Lactic acid also stops muscles contracting efficiently.
Oxygen debt
- Oxygen debt refers to the extra oxygen required after exercise to oxidise (combine with oxygen) lactic acid and remove it from cells.
Repaying the debt
- Blood transports the lactic acid to the liver, where it reacts with oxygen to produce carbon dioxide and water.
- Heavy breathing after exercise helps to repay the oxygen debt by taking more oxygen into the lungs for the break-down of lactic acid.
- A fast heart rate helps transport lactic acid from muscles to the liver.
Test yourself on Oxygen Use & Debt
What is the toxic byproduct of anaerobic respiration?