Anaerobic Respiration
- Anaerobic respiration is a process that occurs in the absence of oxygen
- Glucose is incompletely broken down to release energy and lactic acid
- This occurs when the body can’t supply enough oxygen for aerobic respiration, such as during vigorous exercise
- When we exercise vigorously, our muscles have a higher demand for energy than when we are resting or exercising normally. Our bodies can only deliver so much oxygen to our muscle cells for aerobic respiration
- In this instance, as much glucose as possible is broken down with oxygen, but some glucose is broken down without oxygen, producing lactic acid instead
The oxygen debt
- An oxygen debt occurs as a result of anaerobic respiration
- Lactic acid builds up in muscle cells and lowers the pH of the cells (making them more acidic)
- This is harmful to the body as it could denature the enzymes in cells so lactic acid needs to be removed by oxygen
- This is the reason we continue to breathe heavily and our heart rate remains high even after finishing exercise - we need to take in oxygen to oxidise the lactic acid that has built up during anaerobic respiration
- This is known as ‘repaying the oxygen debt’
- Anaerobic respiration is represented by the equation:
Word equation for anaerobic respiration in animals – some bacterial cells respire in this way too
Examiner Tip
There are other types of anaerobic respiration, such as in yeast, but you are not required to know the details of this.
