Aerobic and anaerobic respiration

In a nutshell

In order for the body to function, energy is needed. Energy is gained from food when it is released into the cells during a process called respiration. There are two types of respiration: aerobic and anaerobic.

Respiration

Definition

Respiration is a chemical process in which energy is released from the breakdown of glucose.

Respiration occurs in every single cell in the body at all times. The energy that is released is used for important things including contracting muscles, maintaining homeostasis, and metabolic processes. Respiration is an exothermic reaction, as energy is being transferred to the environment. There are two types of respiration: aerobic and anaerobic.

ATP

The energy that is used in the body is released from a molecule called ATP, or adenosine triphosphate. Almost all processes in the body require ATP to give energy for its reactions. Free energy is released when a phosphate molecule is removed from ATP.

Aerobic respiration

Aerobic respiration occurs in cells when there is lots of oxygen available. In aerobic respiration, glucose and oxygen produce energy, carbon dioxide and water. It is the most efficient method of transferring energy from glucose.

​$$glucose+oxygen \rightarrow carbon\ dioxide + water$$​​

​$$C_6H_{12}O_6+6O_2\rightarrow CO_2+H_2O$$​​

Anaerobic respiration

Anaerobic respiration occurs in cells when there is no (or not enough) oxygen available. In anaerobic respiration, glucose is converted into energy and lactic acid. It is less efficient than aerobic respiration, as it transfers less energy from glucose.

​$$glucose\rightarrow lactic\ acid$$​​

Vigorous exercise

An example of when anaerobic respiration occurs in humans is during vigorous exercise. During this type of exercise, the body is unable to supply enough oxygen to the muscles through the blood. As a result, the muscle cells need to respire anaerobically to produce enough energy to keep going. The lactic acid that is produced during anaerobic respiration builds up in muscles, and this causes the painful cramping sensation that people experience during exercise.

Plants and fungi

Anaerobic respiration in plants and fungi is slightly different to in animals. This is because, instead of producing lactic acid, they produce ethanol and carbon dioxide.

​$$glucose \rightarrow carbon\ dioxide + ethanol$$​​

Comparing aerobic and anaerobic respiration

There are many similarities and differences between aerobic and anaerobic respiration.

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