In our daily life, we perform many activities – we talk, walk, move around and grow. To perform all these activities, we need energy, and this energy is obtained by the process of respiration.
When we go underwater swimming without an oxygen pump, then after sometime we experience relentlessness, and we feel an uncontrollable urge to breathe. A Scottish physiologist, J. S. Haldane was the first person to observe that a small part of the brain triggers quicker breathing with an increase in the concentration of CO2 in blood. Now the question is why this CO2 accumulation takes place and from where do we produce CO2 in the body? The food which we eat daily breaks down and forms glucose molecules which in turn are oxidized to provide energy and release CO2 as the byproduct. Carbon dioxide molecules released as the byproduct of respiration are not utilized in our body processes, and so they need to be released out of the body at regular intervals. All the members of homo sapiens inhale oxygen and exhale carbon dioxide. This transfer of gases takes place through two organ systems:
Transfer of carbon dioxide and oxygen at the cellular level takes place in the circulatory system. The circulatory system is an organ system which performs the function of circulation of blood, transfer of nutrients, carbon dioxide, hormones and blood cells to and from the cells in the body. Each cell of our body needs to be supplied with oxygen and glucose for a proper functioning of the body. In the circulatory system, glucose is taken from the digestive system and from the respiratory system they carry the oxygen and transport it to every cell of the body. At the cellular level glucose and oxygen are mixed and broken to form energy content, and carbon dioxide is released as a byproduct. Through circulatory system carbon dioxide is sent back to lungs which pass it to the nostril and is expelled out of the body. To get a better understanding of the process of respiration watch the video.