Respiration is a biological process involving the exchange of gases and the production of energy in living organisms. It has two related but distinct meanings:
Physiological Respiration
Physiological respiration refers to the transport of oxygen from the external environment to the cells within tissues, and the removal of carbon dioxide from the cells back to the environment. This process involves breathing (ventilation), gas exchange in the lungs (alveoli), and circulation of blood to distribute oxygen and remove carbon dioxide. In mammals, breathing in (inhalation) actively brings air into the lungs, while breathing out (exhalation) is mostly passive. This system maintains the balance of gases in the lungs and blood necessary for cellular function
Cellular Respiration (Biochemical Definition)
Cellular respiration is a metabolic process that occurs inside cells where organic molecules like glucose react with oxygen to release energy. This energy is stored in molecules such as adenosine triphosphate (ATP), which cells use for growth, repair, and movement. The process produces carbon dioxide and water as waste products. Cellular respiration can be aerobic (requiring oxygen) or anaerobic (without oxygen), with aerobic respiration being the most common in humans and many other organisms
Key Points:
- Respiration is not the same as breathing; breathing is the physical act of air movement, while respiration includes the biochemical energy-producing processes inside cells
- Aerobic respiration uses oxygen to break down glucose, producing a large amount of energy (ATP), carbon dioxide, and water.
- Anaerobic respiration occurs without oxygen and produces less energy, often occurring when oxygen is scarce
In summary, respiration encompasses both the physiological process of gas exchange and the cellular process of energy production through oxidation of nutrients.
