The process of gas exchange is where the respiratory gases, oxygen and carbon dioxide, move across an organism 's respiratory membranes in opposite directions in response to the independent concentration gradients which drive these gases from areas of high concentration to low concentration. The transport of these gases can occur between the air or water of the external environment and the body fluids of the internal environment. To extract energy from organic molecules like fatty acids, amino acids, and sugars, cells need oxygen. This process also produces carbon dioxide which must be transported and disposed. For gas exchange to occur its surface must be moist because the gases need to dissolve in water to diffuse across the membrane, thin enough for the gases to diffuse across, and have a large surface area. A large surface area means more oxygen coming in and more energy being produced.
Gas Exchange in Insects
The gas exchange system of an insect is always at a risk of drying out due to them living on land. This is why the gas exchange system of an insect is internal, so as much moisture as possible is held in due to the humidity inside the insect’s body. Insects get oxygen from the air which has a high concentration of oxygen compared to in water, or in a higher altitude. Air is also the easiest to …show more content…
For fish to take in enough oxygen a lot of water must flow over the surface of the gas exchange system. Air is much easier to ventilate than water is, so fish must use a lot of energy. The gas exchange system is close to the surface of the body but not deep inside as in water there is no risk of the surface drying out. Fish have blood which carries the oxygen to their body cells, but they require a way to transfer this oxygen into their blood from their surrounding environment. This is why fish use their gills as their gas exchange membrane, paired with a counter current exchange system in the blood